S-1A Propane Detector w/ Plug-In Sensor and Solenoid ValveThis is a simple, single channel propane fume detector that features a plug-in sensor and a Var-A-Brite indicator lamp that brightens during the day and soften at night.Complete unit includes display module, one propane sensor and 20 feet of connector wire.The standard two-inch display module features a circuitry test and alarm horn silence functionOn / off switch opens and closes solenoid with the touch of a button