If you've removed the under-hood factory fuel filter in your 2007.5-2018 Ram 6.7L to install an aftermarket kit, you know the water in fuel light turns on the moment you unplug the factory harness. This Fuel Sensor Fooler prevents the light from turning on for good. This won't affect the primary water/fuel separator on 13+ models, so fret not there.
Installation is as follows: unplug the harness from the factory WIF sensor, and plug this in, it's really that simple.