M42 screw mount lens to Leica M L/M mount adapter macro focusing helicoid - M8 M9 M-E Typ 240

This is macro focusing adapter, extension of helicoid ring is about 27mm to 59mm.
Best fit for macro photography, also support focusing infinity at closure.

This adapter allow you to use M42 (42mm x 1.0) mount lenses to fit on Leica M mount camera body.

Using this adapter, although the lens will fit physically, automatic diaphragm (AE metering), or any other functions are not retained using this adapter. In this case the user will need to meter in "stop-down mode" since the lens does not have the ability to have its aperture controlled by the camera body.
Aperture-priority works on most cameras, however a preset exposure compensation may be required on some cameras.
There is no rangefinder coupling, so you need to do "lens scale-focus", the built-in light meter still works fine. And if you use with a M8 and new models, you will still have control over exact framing and composition.