Aqua Sphere Men's Aqua Skins-Rashguard Thermo-Guard technology provides warmth and maximum flexibility and range of motion in the legs and hips 0.5-1mm Glide Skin neoprene offers increased speed and freedom of movement in water due to a low drag coefficient Double-lock Collar offers maximum comfort while keeping water out All Aqua Sphere Aqua Skins have an athletic, European style cut and we recommend,that you choose one size larger than you usually would to accommodate for the different cut of the Aqua Sphere Aqua Skins.