This is an adapter to convert an L39 lens to an M mount. A half-cut type mount adapter. Brand new, unused, and the build quality is excellent. It can now be used with lenses with infinity lock levers, which were previously unusable with the round type L-M ring. This adapter allows you to mount Leica L39 lenses on Leica M bodies. It's made of brass, black chrome-plated, and Teflon-coated. It's a black type designed to minimize internal reflections, which are particularly impactful on digital cameras. Of course, it's also recommended for film cameras. (Some high-end M lenses have the inner side of the mount painted black.) - Model: L-M28/90 - Compatibility: L-M ring half-cut type - Accessories: Instruction manual - Package: Blue box Thank you for viewing.