The Novoflex Lens Mount Adapter allows a Leica R type lens to be mounted onto a Leica M type camera.
Although the lens will fit physically, automatic diaphragm (AE metering) or any other functions are not retained using this adapter. In this case you will have to meter in "stop-down mode", since the lens does not have the ability to have its aperture controlled by the camera body.
Reviews Novoflex Lens Mount Adapter - Leica R Lens to Leica M Body