21.0 Cu. In. 3.5" dia. round fixture support box for use with nonmetallic sheathed cable - Machine tapped fixture holes, ground strap - New work residential construction 2 HR fire resistive walls and ceilings (50 lbs. fixture support) - Polycarbonate - thermoplastic box - Size: Depth=2 13/16", Dia=3 1/2" - Mount with Adjustable bar hanger - max 16" on center Joist application