I bought these to wear over thin liner gloves. I had the same type of mitten, but a cheaper version, in size medium which was a tight fit, so I ordered a large. Wore the Lost Coast Fingerless Mitts on two hikes. They fit like mediums, but these are very warm unlike the ones they replaced. While hiking the pinky would come out of the mittens while using the hiking poles. Used them in temps around 10 degrees, windy and the last hike had wind gusts up to about 30 mph.