20.5 Cu. In. single gang electrical box for use with nonmeatllic sheathed cable - Machine tapped device holes, offset gauge marks, leveling ribs, rigid hard box construction, no distortion with high temperatures, shatter resistant with low temperatures - New work residential construction 2 HR fire resistive walls & ceilings - Fiberglass reinforced polyester - thermoset box - Size: D=3 1/4", W=2 1/4", H=3 13/16" - Mounted with reverse angled mid nails