According to the following:
Could this be for:
ETX/NexStar/NX4Threads (1.375"-24)
Meade's ETX telescopes with apertures from 90mm to 125mm,
Celestron Nexstar 4SE telescope,
Some relatively newer Celestron C90 spotting scopes, and a few other small Maksutov-Cassegrain telescopes.
https://agenaastro.com/articles/guid...ained.html#etx
Cheers
Dennis