This is an extender mount for the Kaytee Silent Spinner. It moves the wheel away from the bars by about 2cm.

In our hamster's cage, it was not possible to use the standard bar mount due to the fact that the wheel would then rub against the sidewalls of the lower half of the cage. The included metal feet are nice on a solid surface, but useless if you give your hamster any decent amount of bedding to burrow. I had to clear the wheel every day from the surrounding bedding to allow the hamster to run during the night.

This mount plugs into the existing mount just like the metal feet do. This was designed for a 6.5" Silent Spinner, and was not tested on any other wheel. It is also designed for a dwarf hamster, so this doesn't necessarily need to be extremely strong.