Winland ElectronicsW-S-S Enviroalert Water Presence Standard Surface Sensor; Supervised

I like the fact it has a circuit monitor built in (EOL resistor) that provides a warning if the wire gets cut, etc. The only thing that night need to change is the contacts are flat on the surface where you place the device. If that surface is metal (one of mine needed to go into the catch pan on my hot water heater) then you must provide an insulator or it will go into alarm without water. Otherwise it is a great design.