A T2 thread, also written T-2, has a diameter of 42mm and a thread pitch of 0.75mm. It is also sometimes written as M42x0.75.
The low pitch distinguishes it from other M42 threads.
ASToptics
T2 ADAPTER FOR TELEVUE POWERMATE 4X
$ 86.00
ready for shipping in 24
h
Meade
Basic Camera Adapter 1.25"
$ 75.00
ready for shipping in 24
h