The essentials:
- enables long exposure
- Equipped with a tapered thread

It is well known that the focal plane shutter on the Leica M is particularly vibration-free. However, for long exposure times, there is no getting around a tripod and a cable release. The cable release for the Leica M, which is equipped with a tapered thread, is screwed into the shutter release thread, and a locking screw makes it easier to use for long exposures in setting B.