Prevent false fire alarms without restricting legitimate fire alarms. The Stopper II consists of a polycarbonate shield and frame. When the shield is lifted to gain access to the actual alarm, it sounds a warning horn, calling immediate attention to the person who is tampering with the alarm. Alarm sounds at 95 dB and continues until the cover is snapped back onto the frame. Unit fits virtually all manual pull stations up to 5-1/2"W X 7"H X 2 3/4"D. Unit operates on one 9-volt battery, included.