This is an adapter for attaching Yashica/Contax mount lenses to Sony E-mount cameras (right side in the photo). I used it with my camera (α7III) without any issues, with room to spare at infinity focus. A helicoid adapter is also included as a bonus (left side in the photo). When I purchased it, infinity focus was insufficient, so I modified it to achieve infinity focus. I am selling it because I have switched to a camera with a different mount.