Underwear (long johns) US LVL 1 is an element of the first layer of clothing, used when its chilly or during intense activities in an environment that requires leg skin protection. Made of Helikon-Tex® Quick Dry polyester fabric, these thermo-active pants wick moisture away from the body, leaving the skin dry and allowing you to comfortably carry out activities. Flat seams minimize the risk of chafing.