Octagon Outlet Box Covers: Application - General Ceiling Outlet; Shape - Octagon; Material - Steel; Box Diameter in inch - 4; Box Depth - in - 2-1/8; Capacity - cu-in - 21.0; Knockouts/Sides-Bottom - (1)1/2" - (1)1/2"; Clamps - NM Cable; Mounting Hardware - Bracket, 90 Deg. To Joist