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.

TS Optics
short T2 Helical Focuser & Adapter
RRP:
$ 108.00
Our price:
$ 75.00
ready for shipping in 24
h

ZWO
Helical Focuser 1.25"
( 5 / 5 )
$ 108.00
ready for shipping in 24
h

ASToptics
1.25" helical focuser (M42/T2)
$ 97.00
Product can be shipped as of 01.06.2025

Artesky
rotator T2 (M42 x 0,75)
$ 91.00
Product can be shipped as of 01.04.2025