The STI9632 is designed to protect clocks and security box alarm bells from vandalism and accidental damage. Constructed of 9 gauge galvanised steel, and coated in white plastic. Suitable for indoor and outdoor locations. Will not rust. Easy to install with the included fixing kit. Removes quickly for routine maintenance or repair. Measures 420mm in diameter and 152mm deep. Please phone to inquire about the entire line of STI stopper products for protection of smoke detectors, cameras, lights and other fixtures.