ZWO M54M-M48F-2mm Adapter - ZWO-M54M-M48F-2

M54-M48-2 adapter is independently developed by ZWO and mainly used for connecting to 2"EFW and M54 filter drawer.

The thickness of this adapter is 2mm.

The best solution of 55mm back focus length

https://astronomy-imaging-camera.com/tutorials/5-connection-methods-to-get-55mm-back-focus-length.html