Perhaps the best and highest quality manual adapter I have ever used.
Very sturdy and well-made, it fits perfectly on the body (a7R II & a6500) just like lenses fit perfectly on it

I use the Canon EF mount for most of my vintage lenses as they easily adapt with the corresponding adapter and work very well without needing to have huge mirrorless adapters attached to each lens for quick changes, nor do I have to screw and unscrew in the case of m42 lenses. Vintage lenses have a huge advantage over modern ones when it comes to focusing, and that is the fixed infinity hard stop, the point where the focus ring stops at infinity, which is factory set to be exactly where the lens delivers maximum sharpness at very far distances. This is very convenient in landscape photography (or video, of course), astrophotography, and generally anything that requires precise focus at very far distances (infinity). Having tried several adapters for different mounts, unfortunately with cheap adapters, you are never sure if they are made with enough precision to support infinity focus as well as a camera with the specific mount. The K&F Concept adapter is made with absolute precision and fully supports infinity focus. Also, the build materials seem to be very good, the adapter has perfect fit and both the body and the lens attach with the right resistance without being loose or having any play. Internally, it is built like a DSLR body so that internal light reflections that result in flares or overall degradation of image quality and sharpness are not created. Aesthetically, the orange back of the adapter matches perfectly with the Sony E mount Alpha cameras, so it doesn't look out of place on the body. Highly recommended.