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. As their polyester-coated cousins, these Stoppers feature 9-gauge steel wire construction in a weblike design that creates a web of protection against abuse. Three sizes available - two for flush mounting and one for surface mounting. For all sizes, the L.E.D. indicator on the protected smoke detector remains clearly visible.