I believe it is just a float type sensor in the tank. Presume you have an electrical connection to your tanks.
We have them, but I don't find them great and don't really need them anyway.
I don't rely on the auto switchover valve on the regulator either, I like simple!
I just leave one tank only open. When gas runs out, I switch to the full tank and get the other one filled !
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.