Safe-T-Alert 40 Series Professional LP Gas Alarm, flush Mount. Designed for the rugged RV environment. Ideal for Class A motorhomes, Class B van campers, Class C mini-motorhomes, travel trailers, fifth wheels, truck and folding campers. Fully operational during mute. Mute does not override detection circuit, giving you full time protection. InteleCheck Circuit means no false alarms from temporary exposures to LP Gas/Propane, aerosol cleaners, hair spray and other flammable gases. Micro current technology saves precious battery power. Long life; self clearing sensor is maintenance-free. Loud 85dB alarm alerts you to the presence of hazardous propane vapors. Test/Reset Button, used to temporarily silence alarm during ventilation. Tests all the detector's functions with one touch. Operates on 12VDC. Dimensions: 4.8 inches W x 3.4 inches H x 1-1/4 inch D. 3 year limited mfr. warranty. 40-442-P-WT