M42 screw mount lens to Canon EOS M EF-M mount adapter Macro Focusing Helicoid - M2 M5 M6 M50 M100
This is macro focusing adapter, extension of helicoid ring is about 27mm to 59mm.
Also, it is very well made (of brass and aluminum) adapter, which will allow you to use Carl Zeiss, Pentax or other brands M42 (42mm x 1.0) screw mount lenses on Canon EOS M EF-M mount APS-C camera.
Best fit for macro photography, also support focusing infinity at closure.
Switching on "Release shutter without lens" in custom menu C.Fn7, then switching shooting mode to M (manual) is recommended.
You can also use an M39-M42 adapter ring (also available in our store) to fit M39 lenses with this adapter.