Leviton 9874 Porcelain Outlet Box Mount, Incandescent Ceiling Lampholder, Keyless, White Perfect for closets, basements, Utility rooms 2 Terminal Screws with Cage Lip Fits 3-1/4" Outlet Boxes,the diameter of the base is 3-3/4" Max. Lamp Wattage: 660W Mounting Type: Twist-lock