This harness from AVS is designed to wire up an AccuAir e-Level or SwitchSpeed system to an AccuAir ENDO-VT tank. AccuAir requires you to follow a complicated wiring diagram and solder a bunch of wires together to get your ENDO-VT to work with their own e-Level and SwitchSpeed systems. This harness from AVS is the perfect, no solder solution.
The 40 inch version of this harness will plug into an e-Level or SwitchSpeed ECU that is centrally mounted on a 5 gallon ENDO-VT tank. If you're running a pair of 3 gallon ENDO-VT tanks and want to mount one on each side of the vehicle, you'll want to go with the 72 inch version of the harness instead.