This is an adapter to convert an L39 lens to an M mount. A half-cut type mount adapter. Beautiful condition, the build quality is as expected. It can now be used with lenses with an infinity lock lever, which were previously unusable with the round type L-M ring. This adapter allows you to mount Leica L39 mount lenses on Leica M bodies. It is made of brass, black chrome-plated, and Teflon-coated. The black type is designed to minimize internal reflections, which are particularly impactful on digital cameras. Of course, it is also recommended for film cameras. (Some high-end M lenses have the inner side of the mount painted black.) - Model: L-M50/75 - Compatibility: L-M ring half-cut type - Accessories: Instruction manual - Package: Blue box Thank you for viewing.