I would say it’s good, but not the best. You need to be very careful with how much you tighten the adapter holder screw, as tightening it too much can create a dent. There are also some areas where light passes through, but it shouldn’t affect performance too much.
The included glass is very fragile, so you need to handle it carefully. I bought this mainly to mount my 67 mm lens adapter, and for that purpose, it does the job.
