Wheelchairs with a tapered seat have frame tubes that converge towards the front. This single piece ring is shaped for that geometry in the smaller round tube diameter, so it sits square on the frame.
It holds the Klaxon crossbeam in the correct position and alignment, which matters because a linking system that sits crooked makes attaching the power add on harder and puts uneven load through the frame.
Fitting is a job for an authorised technician, who will confirm the ring suits the tube and position it against the crossbeam. Once it is on, it stays on the chair. If you are specifying a linking system for a client on a tapered seat chair, measure the tube at the mounting point first.






