The Unit Switch (US3 / 720070-1) allows the user to view sonar and temperature information on two different fishfinders from one transducer.  This toggle switch allows you to alternate from one transducer to the other transducer.  

The main application for the unit switch is to allow a user to have one transducer mounted on the boat, generally on the transom or in-hull, connected through the switch to two different fishfinder displays at different locations on the boat.

In the case of the two units being located at significant distances from each other the user might also have to purchase a 10' or 30' transducer extension cable. In this application a user could mount a fishfinder on their console and switch to this unit while sitting at the console. When the user wanted to move to the other location on the boat for fishing they could activate the switch and view the sonar and temperature information on another fishfinder located at the desired position.

It is recommended that you use dielectric grease on these connectors if there is any chance that this switch might come into direct contact with water.

Boats with fly bridges are a prime target for this application. In addition, we also have an Ethernet solution for those Humminbird products that are Ethernet ready.  There are several different lengths of cables for those products.  Not only does this allow you to share sonar information but it also allows you to share GPS information.