I bought this protector for my series 9 Apple Watch, 41mm, and I can confirm it fits perfectly. I use it together with a Rhinoshield casing, and the two are perfectly compatible. For once I have to say that the "Super Easy Installation" promise is almost 100%: I say "almost" because when pulling out the first of the two films covering the glass, part of it was teared (design fault), so that a good third of the film was left in place. With a minimum of fumbling about I got it out though, and the good news is that I now have a cover that fits perfectly, without bubbles, perfectly positioned, and all accomplished in the space of a couple of minutes. Fitting the cover from another provider on an older watch was a pain, and after spending about half an hour trying to fit it, still there was air. So the mechanism does the job, and easily, and very happy to recommend as far as this aspect is concerned. Hope the protector is strong and does its job well, but only time will tell!