Safety Technology International, Inc. STI-9604 Steel Web Stopper, for Mini Smoke Detectors, Flush Mount, Protective Coated Steel Wire Guard UL Listed protector for areas where abuse to smoke detectors is severe Patented weblike octagon shape of 9-gauge coated steel wire makes it extremely difficult to break Simple removal for servicing of smoke detector Fast and easy installation 3 year guarantee against breakage in normal use