I have found the K&F Concept adapters well made and all mount easily without being too tight or loose. They make 2 different mounts, one cast metal, the other being chromed metal which are the ones I seek.
20/01/2020
This is the 2nd revision of the K&F adaptor. I also own the first. The 2nd revision is a significant improvement on the already stellar original. The adaptor feels sturdier and a bit heavier (in a good way). the camera mount is now made of chrome and the inside is now coated to prevent internal reflections. The first version is still available for a couple of dollars less but do yourself a favour and get this version.You can tell this version from the original in pictures by the camera side mount which is chrome in the new version and black in the original.
23/12/2018
Adapted a vintage lens to my Sony A7r3. Wonks as expected for a great price!
15/12/2018