UL Listed protector for areas where abuse to smoke detectors is severe. STI borrowed from nature's master builder the spider, to create a web of protection from vandalism and accidental damage with this UL Listed wire guard. This unit is constructed of 9-gauge steel wire with corrosion resistant polyester coating. Cover is for surface mounted smoke detectors. Backed by a lifetime guarantee. As all STI protective covers, this Steel Web Stopper is backed by a lifetime guarantee against breakage in normal use. Installation and servicing are easy. Highly recommended for areas where abuse to smoke detectors is severe.