The Arlington Round Low Voltage Mounting Bracket provides easy installation of low voltage smoke detectors and moreIt adjusts to fit 1/4 inch to 1-1/2 inch wall or ceiling thickness. It is UL/CSA Listed. Bracket is its own template for cut out. Trace hole along the inside diameter of the bracket. Cut along the outside of the line. Non-metallic - better than metal and costs less too Adjusts to fit 1/4 to 1-1/2 in. thick wallboard, paneling, or drywall Mounting wings hold bracket securely against wall when screws are tightened Thin front lip seats better on drywall - keeps wall plate flush to wall ARLINGTON LOW VOLTAGE MOUNTING BRACKETSArlington's non-metallic, Low Voltage Mounting Brackets are the time and money-saving solution for faster and easier mounting of Class 2 communications, computer and cable TV wiring. Designed to mount wall plates flush, their mounting brackets have features that deliver a better-looking, easy to install job, specially designed screw holes, thin front lip and more.