4” pre-galvanized steel octagon ceiling fan support box with old work bar hanger, 1-1/2” deep, 15.8 cubic inches. Drawn construction with 3 - 1/2” knockouts. Bar hanger is expandable for joists spaced from 16” to 24”. Maximum recommended loads: 35 lbs. for fans and 50 lbs. for fixtures. For use with conduit or non-metallic sheathed cable.