Hubbell-Raco 7823RAC 2-3/8-Inch Deep Round Non-Metallic Electrical Box with 4 x NMSC Clamps, 2 x Captive Nails with Ground Plate, 4-Inch Durable polycarbonate construction Self-griping nmsc wire entry clamps are integral part of the box 20.0Cu. In. Capacity Not designed for ceiling fan support The maximum support load for a static fixture is 50 pounds