Safety Technology International Inc.
STI Universal Stopper
This STI Universal Stopper (STI-13420FR) helps prevent false fire alarms while it guards against accidental or intentional physical damage. The interior horn is triggered when the cover is lifted, attracting attention before the pull station is activated. The indoor/outdoor clear polycarbonate cover is a waterproof Type 4X cover with a 105 dB horn, enclosed back box and sealed mounting plate. It is sized to fit most pull stations and has a high strength continuous hinge. Other mounting options include surface or flush and with or without a horn. The product is designed to comply with ADA (less than 4 inches in depth) and is UL/cUL Listed.
http://www.sti-usa.com/Products/Universal-Stopper-with-Horn-Enclo-STI-13420FR.htm