Good build quality but no better than at least some other cheaper "generic" Chinese adapters
These seem to command a higher price than more generic Chinese adapters, however I don't really think that they should. I have several of these for Fuji X mount and they are all just a tiny bit loose when fitted, allowing some slightly disconcerting wobble. The much cheaper generic one that I have actually seems to fit better. Having said that, they do the job perfectly well, and I have not had any problems with them. The build quality is very nice and sturdy, and the design looks good on camera.
Only tested on one lens, but works well and for less than £25 I can use my Nikon lenses on the Fuji, saved a packet! Just need to remember that there is no digital connection so it's all manual, but it's the photo that counts.