I always wear a large or medium in the FITS performax and windpro. I was looking for another pair of winter from FITS since I love them.....but these ran VERY small. I bought a large, and they are short in the legs, tight in the legs, and very short in the inseam. I wore them ( and had to constantly pull them up) in 35-40 degree windy weather and was fine. The stickiness was good. So definitely size up if you want to try them.