I bought this after having already bought another EF-FX adapter which is actually the same unit but sold under a different branding, Beschoi. (This is not unusual; all these generic adapters from China and Korea get sold under multiple different names, just as some cheap lenses also do.) Strangely the one sold by Beschoi, despite looking absolutely identical in every way and measuring the same, fit perfectly on older cameras and extension tubes but was unusually tight on a newer camera. Since I was not the only user to encounter that problem and nobody was reporting the same issue with this K&F-branded version, I decided to take a chance and order this as well.Despite indeed being identical in every single way that I can tell with digital calipers, this K&F one isn't tight on the newer body like the Beschoi one is, while also feeling just as solid on the older bodies and extension tubes. It does indeed seem that Beschoi got a batch which was a tiny fraction of a millimeter different in some imperceptible way and K&F got a faultless batch. This is something I have only experienced with this specific EF-FX model; I have other adapters, ones branded both by Beschoi and K&F, and none of them are any better than others. As far as I can tell the Beschoi and K&F products are exactly the same except for the EF-FX adapters where some tiny, tiny variation has messed up the Beschoi ones on the Fujifilm X-H1 and X-T3 bodies.Other than that, this is the same adapter sold under other names and it doesn't appear to be made of any different materials, no text is any better applied, the lens release switch feels identical, etc. That is to say that it feels like a <£20, basic adapter. This one just happens to fit on one camera body slightly smoother than an other-wise identical one.To that end, I'd advise that for all other mount variations you should shop around and try to get one of the versions with different branding as the K&F branding is more expensive for the same product, but for the EF-FD specifically, the K&F-branded ones are the ones that definitely fit right.