Hubbell-Raco 7122RAC Old Work 2-13/16-Inch Deep Round Non-Metallic Electrical Box with 4 x NMSC Clamps, 3-1/2-Inch Durable, lightweight polycarbonate construction Self-griping non-metallic sheathed cable entry clamps are integral part of the box Not suitable for ceiling fan installations Wrap-around metal clamp secures the box to sheetrock 18.0Cu. In. Capacity