Product DescriptionThe Potter CLNGBB Surface Back Box is constructed of durable plastic andis fully compatible with the ceiling mount strobes and horn/strobes.Features ANSI/UL listed for indoor use 1/2" conduit knockouts with metal washer reinforcement Wiremold knockouts for 500, 700 Series and pendulum mount Unit Dimensions: 6.2" (15.75 cm) round x 1.67" (4.24 cm) deep Screw heads hidden Available in red or off-white