Safety Technology International, Inc. -STI 1230 Stopper II without Horn with Clear Spacer, Protective Polycarbonate Cover - This unique and patented device has been helping stop false fire alarms around the world for almost 30 years without restricting legitimate alarms. This tamperproof, tough polycarbonate cover is ideal for schools, hospitals, nursing homes, stores, hotels and public buildings of almost every kind. Cover is connected to the frame by a cable; when cover is lifted it hangs from the frame by its cable. 3 year guarantee against breakage in normal use. UL Listed to U.S. and Canadian safety standards. Polycarbonate rated -40 degrees F to 250 degrees F (-40 degrees C to 121 degrees C). Safety Technology International, Inc. "We protect the things that protect you"