It will allow to use M42 universal screw mount lenses (Zeiss, Pentax Takumar, Yahsica, Praktica, Mamiya, Zenit) on NIKON F SLR cameras (such as D3200, D5200, D7200). 

It might not focus to infinity on most M42 lenses. For that you have to get adapter with infinity focus correction glass elements. 

And some older lenses aperture might not work. It will work only in M mode on digital.

Some Pentax screw mount lenses will work good, and it will focus to infinity.

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