This 12V hard wired alarm is complete with advanced technology that includes mute button that silences alarm while your RV is ventilated and a rapid recovery sensor which resets the alarm when silenced, also reactivates the alarm if dangerous levels of Propane remain. This product is listed to UL. It is built for the extreme RV environment and also has the lowest current draw of similar products on the market, 46 mA. No missing batteries to replace due to the 12 volt power. This product comes with a 3 year warranty. Surface mounted Dim: 5 1/2"W x 3" H x 1 1/2" D.