I chose the Rex Doggles because the design features a wide, single lens which maximizes my dog's field of vision. So many others have 2 lenses which greatly decreases a dog's peripheral vision to the point of functioning more like the blinders they put on racehorses. I think this is actually dangerous for the animal. For me, the widest possible field of vision is the most important feature of any ski goggles I purchase for myself.
The included online suggestions on how to introduce the doggles to my dog were very helpful. He sniffed them out the first time and was fine until I clicked them closed. He barked and jumped away and wouldn't get near them. But I let him check them out again the next day and he was fine and he was rewarded with a treat. Then I put them on and adjusted the straps- he's a 4 year old Sheltie and very trusting so he was patient and let me do all of the adjusting including making sure his whiskers weren't caught in the mask. Again, the first time he wore them he tried to paw them off his face but I told him to stop and rewarded him to make it a fun experience. He's very food motivated so treats helped to build a positive association with the doggles. Now he wears them without issue and, of course, still gets treats for being a good sport. These are the best designed doggles I've found and I highly recommend them.