Adapter that allows you to screw a 31 mm unthreaded filter into an hole designed for a 2″ threaded filter.
The 31 mm filter can be in a metal holder without thread or with no external holder (glass only). Just insert the 31 mm filter into the adapter, put on the cap, tighten it with three hex screws and you are done.
The adapter with attached filter can be screwed into most standard 2″ filter drawers and slots. It fits not only metal threaded holes, but also Astrodevice 3D printed filter drawers.
Expected filter size: 31 mm diameter, 3 mm height.
The space for placing the filter is 31 mm in diameter and 3 mm deep.