Some of us can't wear contacts and we don't want to wear glasses under our goggle (because they fog up and it's uncomfortable). We want prescription inserts! Unfortunately, the options for us are extremely limited. I also must sweat tremendously out of my eyeballs, and have terrible problems with fogging. The only goggle that does any good for me is the Smith Turbo fan goggle. I have a non-I/OX Smith goggle and the lenses are nearly impossible to change without great difficulty. My other Turbo fan goggles also use the Smith adaptor available prior to the OSD2. That adapator sucked! I ended up having to wire it into the goggle so it wouldn't fall out, and I bought a second goggle so I wouldn't have to change lenses. Hauling around two goggles is a pain, though. I thought the OSD2 adaptor would be the solution, since it seemed to be a much better design and I could use one prescription adaptor with both my Smith Pivlock V2 Max sunglasses and my Turbo Fan goggles. But the I/OX goggles sounded like the way to go, since the other Smith goggle lenses are very hard to change. Today the I/OX goggles arrived and the lenses are much easier to change. But the OSD2 adaptor must not fit in the goggle without yet another adaptor. A chat with backcountry said Smith should have that additional adaptor. If not, I guess I'll have to return the goggles. I bought them because of the OSD2 adaptor compatibility (supposedly). I don't understand why someone doesn't make a very simple adaptor that can easily be moved between a solid line of sunglasses and fan goggles. Probably only those of us that can't use contacts and don't want to wear glasses under our goggles understand. But I'd pay big bucks for a system that was truly functional.