Ceiling fan box w/brace, 1-1/2 in deep, 15.5 cubic inch octagon box. Used to hang ceiling fans and light fixtures between joists or structural members safely and securely in old work applications where access is limited. Brace allows simple expansion, adjustable form 16 in to 24 in Recommedned support load for ceiling fan is 35 pounds, for fixtures is 50 pounds. 4 half inch knock outs. Mounting hardware with high strength, hardened screws and instructions included. Acceptable for use in 2-hour rated walls andceilings.