Amongst other uses, the adapter allows the direct connection of the 2.5" PHOTOLINE corrector for APO refractors to focusers with female M63x1 thread, like the 2.5" Starlight Feather Touch focusers or the modern 2.5" rack and pinion focusers from TS.
Lacerta OCTO-PLUS 2-inch eyepiece slide for Newton (guided on 8 ball bearings, with 1:10 microfocus unit and 2" self-centering eyepiece sleeve), for 10inch tube
Lacerta OCTO-PLUS 2-inch eyepiece slide for Newton (guided on 8 ball bearings, with 1:10 microfocus unit and 2" self-centering eyepiece sleeve), for 8 inch tubes