The Alpine Astronomical Baader M68 to 2" UNFI Conversion Ring reduces M68 threads to 2" universal filter (UNFI) threads, which also fit most Schmidt-Cassegrain telescope (SCT) visual back threads. The front (telescope) side has male M68 threads and the back has standard 2" female eyepiece filter threads to mount a variety of gear, including filters and T-2 rings.