This unique and patented device has been helping stop false fire alarms around the world for more than 20 years, without restricting legitimate alarms. Ideal for schools, hospitals, nursing homes, stores, hotels and public buildings of almost every kind. Stopper II consists of a clear, tamperproof, super tough polycarbonate shield and frame that fits over manual pull stations. When lifted to gain access to the actual alarm, it sounds a piercing 95 dB or 105 dB warning horn. Immediate attention is drawn to the area and a prankster will either run or be caught.This new version of the Stopper II is UL Listed for outdoor use.