About the same time I picked up the oil level sensor, I also purchased fuel level sensors. These don’t measure the fuel level. The sensor turns a warning light on when the fuel gets to a certain level. The guy that sold it to me called it an “Oh Shit” warning light. I have it set so when it goes on, it’s time to switch tanks. If both lights are on, its time to head for an airport. Again, I installed it with nutplates.