They are specifically designed for Ruffland Kennels with composite doors using a Ryobi Fan (Model: RYOBI 18V ONE+ Hybrid Portable Fan) that has a hook on the fan itself.
The biothane fan holder itself does not have a hook. It is 3 rings.
If your fan or crate is different in brand, model and size, there is a risk it may not be suited for you.
Note: Fan holders are made to order and may vary slightly in length by a few millimeters as they are handmade.