NMEA 2000 Networks General Info (T-Conn)


Pub. 988-0154-172
Setup and Installation of
NMEA 2000 Networks
General Information
NMEA 2000 is a communication bus network specifically designed for
boats. This is an industry standard developed by the National Marine
Electronics Association(NMEA). To help you get the most out of this
technology Lowrance has introduced a line of products that can communicate over a NMEA 2000 network.
This instruction sheet outlines the basics of what it takes to create a
NMEA 2000 network. It also will explain how to use this network to
connect your Lowrance and LEI products and provide some tips on configuring and using the operational network.
Terminology
There are several key phrases you will need to know before we can explain how the NMEA 2000 system works. Some of these are technical
terms, some of them are names taken from the NMEA 2000 standard
and some of them are our own names developed for clarity. All of them
will help you understand what we are saying.
"NMEA 2000 Network" or "LowranceNET "
When we talk about the NMEA 2000 network we are talking about the
communications link between two or more devices that transfer NMEA
2000 information. "LowranceNET" is the NMEA 2000 networking system developed by Lowrance Electronics. Think of this as a computer
network or the phone wiring in your house. If you pick up a phone in
your living room you can hear someone talking into the phone in the
bedroom.
A NMEA 2000 network is a way to let more than one display unit "listen in" on the GPS antenna's conversation or to let more than one sonar
display unit overhear the messages being sent by a temperature sensor.
You can even view engine diagnostics and fuel level on digital gauges or
display units located anywhere on your boat.
If you have a Lowrance display unit with an LGC-2000 GPS module
installed then you have a NMEA 2000 network. The connectors and
cables that came with your LGC-2000 actually function as a dedicated
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NMEA 2000 network passing GPS signal information along the network (that is, the extension cables) to the GPS display unit. This is a
very limited application of the term "network."
The other end of the scale is a network bus (described in the following
segment) built into your boat with nodes at intervals allowing you to
connect several GPS or sonar display units, temperature or water speed
sensors, digital gauges or any other NMEA 2000 device.
Such a network could display the temperature readings from two different sensors (one at the water surface and another in your live well)
as well as the GPS signal from an LGC-2000 and even the reading from
a fuel-flow sensor attached to your fuel line. The network could share
all of this information with a sonar-GPS combo display unit mounted in
the dash, a smaller sonar-only display unit at the stern and another up
on the bow by your trolling motor. All three display units attached to
the bus would have access to all of the sensor information from every
accessory attached to the network. The network design would look like
the one in the following diagram.
Sonar unit
at bow
Sonar-GPS
unit in dash
LGC2000
EP-35 temp sensor
in live well
Sonar unit
at stern
25' extension
cable
EP-10 fuel flow sensor
EP-35 temp sensor
at water surface
NMEA 2000 network with three sonar or sonar-GPS combo display
units, each receiving position information from the LGC-2000, temperature information from temp sensors at two different locations and fuel
use information from a fuel flow sensor.
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That is the advantage of a NMEA 2000 network. Every display unit,
gauge or sensor attached to the network communicates with all the others.
Of course location, speed and temperature are not the only kinds of information that can be shared. Other capabilities include the ability to share
the amount of fuel remaining in your tanks, detailed engine information
such as oil pressure and fuel efficiency and much more.
NOTE:
You probably noticed there is no transducer mentioned in that list or
anywhere else in this document. The full sonar chart reading from a
transducer takes too much bandwidth for a NMEA 2000 network
which means sonar charts cannot be shared. Every sonar display
unit requires its own transducer to draw charts.
However, if you have a sonar display unit (with a working transducer) connected to the NMEA bus it will share the digital depth
with every other display unit on the network.
"NMEA 2000 Bus" or "Network Bus"
Technically, any physical cable properly installed and used to transfer
network information is a "network bus" but in our documentation we
use this term to refer to the standard manufacturer installation appearing in new boats. This network bus is an installed and operational
network cable running the length of your boat, already connected to a
power supply and properly terminated. Such a bus provides network
nodes at various locations around your boat.
"Network Backbone" and "Network Nodes"
A network bus is built of network nodes spread along a backbone. Network nodes are made by fitting T-shaped connectors into the backbone
(using the sockets on the sides) and attaching a display unit or sensor at
the bottom of the T.
If we stick with the earlier example, the T connectors along the length of
a boat are the equivalent of phone jacks spread throughout a house.
Phones in a home have to be connected to each other to communicate and
in the same way only sensors and display units plugged into the NMEA
network can share information. The backbone is like the phone wiring
that runs throughout a home; it connects these nodes.
Connections found in the middle of the bus will have one or more of these T
connectors with the backbone cables plugged into both sides. Connections
at the end of a network will have the backbone plugged into one side and a
terminator plugged into the other as shown in the following figure.
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Cable from
sensor or
display unit
LEI or Lowrance
device needs an
open T.
Terminator at
the very end
of the bus
Backbone cable
(to rest of bus)
NMEA 2000 network node located at the end of a NMEA 2000 backbone.
All of the T connectors on your boat's network will probably be filled but
if you want to add another node to a working network just add a T connector from LEI (ordering information appears on the back page of this
booklet). If you are adding a Lowrance or LEI NMEA 2000 sensor it will
come with its own T connector making the process even easier.
This T connector allows you to add a device to your NMEA 2000 bus
creating a network node.
The "soft" T connector, shown above with a "hard" T connector, is another
option for connecting devices in a NMEA 2000 network. The soft T works
the same as a hard T. The soft T is used to install a network node in areas
were a hard T will not fit.
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"Linear Architecture"
NMEA 2000 networks are designed using a linear architecture and it is
important for you to maintain this pattern whenever you modify your
network (such as adding nodes).
When we say "linear architecture" we are referring to the way the network's backbone is assembled and to the way you attach T connectors
along it. Note that every T connector has one female socket and two male
sockets. This means you could connect it in two different ways.
You could plug the sensor or display unit into the bottom of the T and
the backbone cable into the side of the T (as we recommend). You could
also plug the sensor or display unit into the side of the T and the backbone connection in the bottom of the T. The sockets would allow you to
make that connection but you would lose linear architecture. Consider
the following images.
Sonar or GPS
display unit
Sonar or GPS
display unit
LGC2000
EP-35
temp sensor
Correct architecture
EP-35
temp sensor
LGC2000
Incorrect architecture
Two possible network designs. The design on the left maintains a linear
architecture while the one on the right does not. You should always
maintain linear architecture when building a NMEA 2000 network.
Both of the network designs in these images contain the same set of
components. Both networks are terminated and all of the connectors
are able to attach together. However, the design on the left is easier to
maintain and expand. It also allows you to make sure the two terminators are at the ends of the backbone. Since the system on the right is
non-linear there is not a clear end.
Always maintain linear architecture when modifying your network.
Just make sure to attach display units or sensors to the bottom of the T.
Attach the sides of the T to other T connectors, to backbone extension
cables or to terminators – nothing else.
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For reference purposes all of the example network designs you will find
in this document show networks built with a linear architecture.
Adding a Network Node
You can add a node anywhere along the network backbone where a connection already exists. This connection could be at the end of the network
(between a T connector and a terminator) between two T connectors, between a T connector and a backbone extension cable or between two extension cables. Wherever you want to add the new node simply separate
the sockets of the old connection and attach your new T connector between them.
Lowrance or LEI device connects to new T connector.
Existing network
node
Add T-shaped connector to add device
to bus (maintaining
linear architecture).
Attach
terminator at
end of bus.
Add a new device to a NMEA 2000 bus by attaching a T connector between two T connectors, between a T connector and the end terminator,
or between two backbone extension cables.
If you want to add a node at the end of the line (as shown in the previous
figure) remove the terminator from the very last connector, securely attach the new T connector, and attach the terminator on the new connector. Either method will allow you to add a device.
NOTE:
If your network only includes one terminator (such as the network
created when a single display unit is connected to an LGC-2000)
you will need to add a Node Kit before you can add additional network nodes. You only need to purchase a Node Kit once. After that
you can add nodes as described in the previous section.
Most manufacturer-installed networks will already have two terminators so a Node Kit will not be necessary.
Adding an Extension Cable
LEI provides LowranceNET extension cables in various lengths so that
you can position all of the items on your network exactly where you want
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them on your boat. Every extension cable has a male connector on one
end and a female connector on the other allowing you to insert it anywhere the network has a connection.
For instance, you might have a cluster of T connectors at the bow of your
boat and attached to the last T on the cluster is a 15' extension cable
running to your console. On the end of this extension cable you could
have another cluster of T connectors and another extension cable running to the stern of the boat where you have more T connectors for more
devices. We recommend you keep your network backbone to less than
about 300 feet (100 meters).
You can also attach an extension cable between a device on the network
and the T connector allowing you to more easily position the device right
where you want it. You should never use more than 15' (about 5 meters)
of extension cable between a device and the network backbone.
Building a LowranceNET NMEA 2000 Network
In 2005, the original equipment manufacturers (OEM) began installing
NMEA 2000 networks as standard equipment in new boats. If your boat
does not have an OEM-installed NMEA 2000 network you will have to
install your own. This instruction sheet will explain how to install a
LowranceNET NMEA 2000 network using cables available from LEI.
Installing a NMEA 2000 network is not complicated. If you can grasp a
few essential concepts you can design a network to fit your needs and
keep it running smoothly.
Power
In order for a NMEA 2000 network to operate the bus must be connected to a switched power source (a power source that you can turn on
and off – generally a switch on your boat's accessory panel). NMEA
2000 networks require 12 volts DC power. If your boat came with a
NMEA 2000 bus it should already be connected to a switched power
source that draws from the boat's battery. To confirm how the bus was
installed, consult your boat dealer or manufacturer.
•
No matter how large or small the network, no matter how many
devices are sharing information along it, a NMEA 2000 network
must be connected to a 12-volt power source to operate.
If you are only running a display unit and an LGC-2000 on the mininetwork as described earlier you will still have to connect the display
unit's NMEA 2000 Power cable to a switched power source in order to
power the network.
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•
Always use a switched power source for your NMEA 2000 bus. Do
not connect the NMEA 2000 Power cable directly to your boat's battery.
You need to be able to turn the network's power on and off.
Extension cable
Data
cable
Sonar unit's power
cable can connect
directly to battery
To network
T connector
NMEA 2000 power cable should connect to switched power.
Only connect the NMEA 2000 power cable for one display unit.
Typical do-it-yourself NMEA 2000 power configuration, using the 3branched power/data cable packed with the display unit.
Many of the devices on the NMEA 2000 bus are "on" and drawing current whenever the network has power – they do not have their own
on/off switches. In order to preserve your battery you need to make sure
your NMEA bus's main power supply can be switched on or off easily.
Most installations simply connect the NMEA power cable to a switch on
the boat's accessory panel.
•
Never connect an additional power source to a NMEA 2000
bus that is already powered. A NMEA 2000 network should
never be connected to more than one power source.
If you are attaching a GPS display unit and an LGC-2000 to an already
powered NMEA 2000 bus make sure you do not connect the display
unit's NMEA 2000 Power cable to another power source.
All Lowrance display units with blue connectors come packed with a
three-branched power/data cable that includes wires to power a NMEA
2000 bus. As stated before, if you are connecting just a display unit and
an LGC-2000 as a dedicated network you will have to attach the NMEA
2000 power cable to a switched power source. Note that this is in addition to the display unit's own power cable which can be connected directly to your boat's battery.
However, it is possible to hook up several sonar or GPS display units to
a single network. If you do remember that only one display unit
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should provide power to the network. Even though all the display
units on the network come with a NMEA 2000 Power cable you should
only attach one of them.
In addition to the three-branched power/data cable that comes with
Lowrance display units Lowrance and LEI provide two other methods of
powering a NMEA 2000 bus. These include a Powered Terminator and a
Power Node. Many manufacturer-installed networks use one of these alternate power sources. If your network already includes either of these
power sources do not connect the NMEA 2000 power cable of any of your
GPS or sonar display units.
OEM factory installations typically use a Power Node to supply power
to the network bus. The red and black leads are connected to a
switched power source, allowing the user to turn off power to the bus.
WARNING!
If you connect multiple power sources to a NMEA 2000
network you could cause severe damage to the network,
attached devices and your boat!
Terminators
In order for it to work properly, a NMEA 2000 network needs to be
terminated with either a single 60-ohm terminator or two 120-ohm
terminators. The most common and preferred setup uses two 120-ohm
terminators – one at each end of the bus. This must be used if you intend to use three or more devices on the bus.
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If you have an LGC-2000 you have seen the small plug (with "60" imprinted in the plastic grip) that comes along with the T connector and extension cables. This little plug is as important to the mini-network as any
of the other parts – this is the one 60-ohm terminator. If your boat came
with an installed NMEA 2000 bus the terminators will already be attached.
The terminators provide resistance necessary for devices to communicate along the network. This communication takes the form of electrical
pulses sent out by the device transmitting information. In order for the
network to operate you need 60-ohms of resistance to pull the network
back to its recessive state after a signal so the next pulse can be heard.
Terminators (either one 60-ohm terminator or two 120-ohm terminators in parallel) are used to create this resistance.
•
Never attach terminators to an operational NMEA 2000 network bus. If it is working it is already terminated.
•
If you are using two 120-ohm terminators it is best to connect them
to sockets on the network as far from each other as possible. Attach
one at each end of the backbone and install all of the network nodes
between them.
Setting up a Network
Lowrance and LEI provide all the cables you will need to create a NMEA
2000 network on your boat. We provide T connectors and extension cables so you can add devices along the backbone wherever you want. Once
you have a working network every sensor you add to it will come with its
own T connector for easy expansion.
Remember that one of the simplest LowranceNET NMEA 2000 networks
is just a display unit with an LGC-2000, one T connector and one 60-ohm
terminator. We will show you how to connect that system in the following image.
60-ohm
terminator
Network port on
display unit
Extension cable
Attach the LGC2000 to the side of
the T connector, for
this setup only.
LGC2000
LGC-2000 direct connection to a display unit.
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When you want to expand that connection into a more extensive NMEA
2000 network with multiple nodes, you'll need to buy a LowranceNET
"Node Kit." The Node Kit comes with two 120-ohm terminators (to replace the single 60-ohm terminator that came with the original kit), a T
connector and an extension cable.
LowranceNET Node Kit for a NMEA 2000 network. Includes a 2 foot
extension cable, T connector, 120-ohm male terminator and 120-ohm
female terminator.
NOTE:
Only one Node Kit is needed the first time you upgrade your network from a simple GPS display unit and LGC-2000 mini-network
to a more expansive network. After that, just buy sensors (which
come with T connectors) or individual T connectors and cables to attach additional sonar or GPS display units.
120-ohm
terminator
Network port
on GPS unit
Extension cable
Attach these two T
connectors together,
or insert an extension
cable between them.
LGC2000
120-ohm
terminator
LGC-2000 and GPS display unit as an expandable NMEA 2000 network.
Compare the two previous drawings. The second one has one T connector
for each device (in this case two) and does not use the 60-ohm terminator
– it has been replaced with two 120-ohm terminators, one at each end of
the backbone. In this case the backbone is just two nodes connected to11
gether but it is now easy to add additional items by inserting new T connectors and backbone extension cables wherever you need them.
Networking 2005 and Earlier Models
NMEA 2000 display units purchased in 2005 or earlier were packed with
a different connector — a Y cable with a 60-ohm terminator.
LGC2000
60-ohm
terminator
This 2005 model packed with Y cable connector.
Y cable
When you want to expand that connection into a more extensive NMEA
2000 network with multiple nodes, you will need to purchase a Node Kit
and an additional T connector. Some installations may also need backbone
extension cables, depending on the size of the boat and the configuration of
the installation. With these new connections, the old Y cable and 60-ohm
terminator are no longer needed and should be discarded.
Adding a New Device to a Working Network Bus
Once your boat has a working NMEA 2000 bus you do not have to worry
any more about power or terminators or configuring cables. Just install
additional T connectors as described earlier and connect your Lowrance or
LEI devices to the network as described in the following paragraphs.
Now, let's start setting up networks. We will assume you are starting
with a mini-network with an installed Node Kit as we described in the
last section (that is, a GPS display unit, an LGC-2000, two T connectors
and 120-ohm terminators on both ends). If your boat came with a
Lowrance NMEA 2000 network installed it will be set up in much the
same way although it will probably already have additional devices attached.
For our first example we will imagine you are trying to add a second display unit which also will receive location information from the installed
LGC-2000.
You would set up the network exactly like the network we described earlier
but add an extra node (the extra extension cable and T connector could have
come packed with the second display unit).
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120-ohm
terminator
Attach all three T
connectors sideby-side, or insert
extension cables
between them.
First GPS
display unit
Extension cable
LGC2000
Second GPS
display unit
120-ohm
terminator
NMEA 2000 network with LGC-2000 connected to two GPS display units.
Notice that we have unplugged the 120-ohm terminator from the LGC2000's T connector, added a new T connector in its place, and connected
the terminator at the new end of the backbone. Always keep the terminators at the ends of the backbone.
Another option for expanding a network would be adding a network node
with a NMEA 2000 temp sensor. Then your sonar-GPS combo display
unit would receive both the GPS signal from the LGC-2000 and the temperature information from the temp sensor.
120-ohm
terminator
Attach all three T
connectors sideby-side, or insert
extension cables
between them.
120-ohm
terminator
Sonar-GPS
display unit
Extension cable
LGC2000
EP-35
temp sensor
Lowrance NMEA 2000 network with display unit,
GPS module and temp sensor.
Or you could connect two sonar-GPS combo display units to the network, an LGC-2000 and a temp sensor. To do that simply add another
node to the network as we discussed earlier.
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120-ohm
terminator
Sonar-GPS
unit
Extension cable
LGC2000
Attach all four T
connectors sideby-side, or insert
extension cables
between them.
EP-35
temp sensor
Sonar-GPS
unit
120-ohm
terminator
Network with two sonar-GPS display units,
a GPS module and temp sensor.
You can continue expanding with new network nodes until your network contains everything you want to include. The following figure
shows the extensive example network we described in the introduction
to this booklet.
In addition to all the display units and sensors you will notice it includes
two 120-ohm terminators and a total of seven network nodes. There is
virtually no limit to the expansion possibilities but we do recommend you
keep your network backbone to less than about 300 feet (100 meters).
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First 120-ohm
terminator
Sonar unit
at bow
Sonar-GPS
unit in dash
Data
cable
Sonar unit's power
cable can connect
directly to battery
LGC2000
NMEA 2000 power cable should connect
to switched power. Only connect the
NMEA 2000 power cable for one display
unit.
EP-35 temp sensor
in live well
25' extension
cable
Sonar unit
at stern
EP-35 temp sensor
at water surface
EP-10 fuel flow sensor
Second 120-ohm terminator
Extensive NMEA 2000 network using LowranceNET cables. Shown: Three
sonar or sonar-GPS display units, each receiving position information
from the LGC-2000, temperature information from temp sensors at two
different locations, and fuel use information from the fuel flow sensor.
Note that only one of the display units has connected the NMEA 2000
power cable (to a switched power source), to power the whole network.
The display units at bow and stern should connect only the units' power.
Connecting to a non-Lowrance Network
Some boats will come with a manufacturer-installed NMEA 2000 network that does not use LowranceNET T connectors. Many of these networks will use the Molex Micro-C T connector shown in the following
image.
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The Micro-C T connector used in some NMEA-2000 busses.
For your convenience Lowrance manufactures a Bus Adapter Cable to
connect Lowrance products to Micro-C T connectors.
To Lowrance unit
or LEI accessory
To NMEA 2000
network port
Micro-C to Lowrance Male converter.
With this adapter cable you can connect the Micro-C plug (shown left in
this figure) to an available network node on your boat's NMEA 2000 bus.
The Lowrance plug (shown right) connects to a Lowrance display unit or
NMEA 2000 sensor.
Looking Ahead
As you probably know the NMEA 2000 communication standard is not
a new concept. It was developed to replace the old standard NMEA
0183. In fact, you might own some Lowrance products that communicate using the NMEA 0183 standard.
NMEA 0183 was developed over a period of many years and it changed
dramatically over that time. So dramatically, in fact, that NMEA 0183
devices developed in the early days of the standard (NMEA 0183 ver. 1)
are no longer compatible with NMEA 0183 devices developed recently
(NMEA 0183 ver. 3).
In order to correct this and to prevent something similar happening
again NMEA decided to adopt a new standard, NMEA 2000, which is a
radical departure from the old NMEA 0183. NMEA 2000 devices will
not communicate with NMEA 0183 devices. The NMEA 2000 was
planned from the beginning to be a consistent system capable of incorporating future growth.
Boats with built-in NMEA 2000 busses have started to appear on the
market and many of the sensors and other products that will provide
information to the network are still being developed by many companies, including Lowrance. NMEA 2000 is the industry's adopted standard and with all the power and versatility it offers you can expect to
see a lot of growth in the near future.
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We mentioned engines capable of reporting detailed operation information along the network. This is one of the major benefits of NMEA 2000
and it is being heavily pursued but like many aspects of the new technology it is still in development. We expect that by mid-2006 most engine manufacturers will be producing engines that output extensive
NMEA 2000 data.
We are dedicated to helping you get the most out of this technology.
Many Lowrance display units (with 5-pin connectors) will require software upgrades to correctly show NMEA 2000 information. Remember
that Lowrance often offers free software updates for their display units
on the web site, www.lowrance.com. As NMEA 2000 technology evolves
you can count on Lowrance to evolve with it, constantly developing to
help you get the most performance possible from your products.
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Notes
18
Notes
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How to Obtain Service…
…in the USA:
Contact the Factory Customer Service Department. Call toll-free:
For Lowrance: 800-324-1356. For Eagle: 800-324-1354
8 a.m. to 5 p.m. Central Standard Time, M-F
Lowrance Electronics and Eagle Electronics may find it necessary to change or end
their shipping policies, regulations and special offers at any time. They reserve the
right to do so without notice.
…in Canada:
Contact the Factory Customer Service Department. Call toll-free:
800-661-3983
905-629-1614 (not toll-free)
8 a.m. to 5 p.m. Eastern Standard Time, M-F
…outside Canada and the USA:
Contact the dealer in the country where you purchased your unit. To locate a
dealer near you, see the instructions in paragraph number 1 below.
Accessory Ordering Information
LEI Extras, Inc. is the accessory source for sonar and GPS products manufactured by Lowrance Electronics and Eagle Electronics. To order Lowrance or
Eagle accessories, please contact:
1) Your local marine dealer or consumer electronics store. To locate a Lowrance
dealer, visit the web site, www.lowrance.com, and look for the Dealer Locator.
To locate an Eagle dealer, visit the web site, www.eaglesonar.com, and look for
the Dealer Locator. Or, consult your telephone directory for listings.
2) U.S. customers: LEI Extras Inc., PO Box 129, Catoosa, OK 74015-0129
Call toll free in the U.S., 800-324-0045, 8 a.m. to 5 p.m. Central Standard Time, M-F, or visit our web site www.lei-extras.com.
3) Canadian customers: Lowrance/Eagle Canada, 919 Matheson Blvd. E. Mississauga, Ontario L4W2R7 or fax 905-629-3118.
Call toll free in Canada, 800-661-3983, or dial 905 629-1614 (not toll free), 8
a.m. to 5 p.m. Eastern Standard Time, M-F.
For Lowrance and Eagle Products
Pub. 988-0154-172
© Copyright 2005
All Rights Reserved
LEI
Printed in USA 101005
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