Safety Technology International, Inc. - STI 1210D Horn/Strobe Damage Stopper and open back box with conduit knockout for signal units. This virtually indestructible Damage Stopper cover is molded of clear, thick UV-stabilized polycarbonate material is designed to stop vandalism or accidental damage. Slots in the door allow horn/alarm to be easily heard. Open back box with conduit knockout for mounting over exposed conduit. MEA Approved and UL listed to U.S. and Canadian safety standards. Allows easy access for any type of service or maintenance. Typical working properties of polycarbonate are -40° to 250°F (-40° to 121°C). 3-year guarantee against breakage of polycarbonate in normal use. Safety Technology International, Inc. "We protect the things that protect you"