This 2"/1.25" adapter lets you use 1.25" accessories in a 2" focuser, such as eyepieces or astro cameras. Its brass compression ring secures accessories without the locking screw scratching their surface. A practical advantage is the built-in thread for accepting 2" filters.
The adapter has a total height of 28 mm and an optical path length of approx. 8.5 mm.