A really sturdy retrofit support for mounting and supporting even a heavy ceiling fan safely. It is easy to slide into an existing ceiling hole, and can expand up to a 24” ceiling joist spacing, then dig in to the wood and tighten by twisting the support 5 to 6 rotations. I could have even done a one-arm pull-up on this without fear after the teeth dig into the joists. Comes with a nifty electrical box the snaps onto the shaft and all hardware. This was a terrific and essential purchase for securely mounting a heavy ceiling fan.