This appears to be a ring used for F-mount series cameras, such as the Konica FS (released in 1961), an old Konica SLR camera. I bought it a while ago thinking I might be able to use it for something, but I've decided to sell it (^.^). I found a page where someone adapted this KONICA FS macro ring to be compatible with Sony E-mount, so if anyone can make good use of it, please consider it. * Instant purchase without comment is OK, but if there are negotiations in progress, I will prioritize the person negotiating, so thank you for your understanding. If you have any other questions, please feel free to ask. I will ship it within 1-2 days via Nekopos (domestic delivery service). Thank you for looking.