RACO RETRO-BRACE is used to hang ceiling fans and light fixtures between joists or structural members safely and securely in old work applications where access is limited. For old work installations ; Brace is adjustable from 16" to 24" joist spacing - simple tool free expansion ; Includes nonmetallic sheathed cable connector, mounting hardware, and instructions ; High strength, hardened screws ; Knockouts in bottom of box allows for easy entry and exiting with cables;.