I was looking for a waterproof, breathable shell mitt to use with boiled wool mittens. There are very few choices on the market. These were to replace some old Marmot shells that I loved but lost. I had purchased a pair of these for my son earlier in the year and thought mediums were a little snug over the heavy wool, so ordered a large. This worked fine. I would have liked just a little more structure in the cuff fabric so they would be easier to pull on, but they work pretty well. Otherwise they fulfill my needs well.