I purchased the Airr Insole and it's much better than the regular insole in my Soucony running shoes. I'm a 7.5 and purchased the size 7-8.5. Fits my 7.5 shoes perfect with no cutting. I think it would be to small for anything over a 7.5 shoe size. If I was an 8 to 8.5 shoe I would get the next size up and cut them to match the sole you're replacing. They do not make my shoe fell smaller and I do not have to get a half size bigger shoe. All's the same just drop the new Airr sole in and feel the difference.