This is a custom adapter for converting Yashica Pentamatic lenses to Leica M mount. It does not couple with the Leica's rangefinder. There is a slight over-infinity focus, but it can still achieve infinity focus without issue. The lens does not lock when attached, but there is sufficient friction to prevent the lens from falling off. This is not a commercially available product, so please refrain from purchasing if you are overly concerned about minor imperfections. Thank you. Return Policy: In the unlikely event that the item significantly differs from the description at the time of sale, we will accept returns and provide a refund. In such cases, we will only process the return through a "transaction cancellation" agreed upon by both parties. Please do not press the "receive" button (as this will finalize the transaction and prevent cancellation).