This is the only M42 male to male telescope adapter I could find. The thread on both ends is 0.75mm. The hole diameter at both ends is 42mm, male thread, and the thread pitch at both ends is 0.75mm. This is the standard size and thread pitch of the telescope and "T-Adaptor". DO NOT confuse the M42x0.75mm thread with the M42 lens or camera adapter. or try an M42 mount camera or lens! Although they are also 42mm in diameter, the thread pitch is 1.0mm. This adapter will "start", but will soon jam, and if you try to force it, you'll smack a thread on something.
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