Arlington LVR1 Low Voltage Smoke Detector Mounting Bracket, Round, Black, 25-Pack When installed, lays flush against wall Bracket is its own template for cutout Durable plastic bracket is less expensive than metal Fits 1/4-Inch to 1-1/2-Inch thick drywall, paneling, or wallboard 4.37H x 4.37W x 2.12D