These heavy-warmth thermal bottoms include our Timberland PRO® FLEX technology maximum mobility features so you can bend, reach, and stretch without restriction, fabric that offers warmth without bulk, and flat-lock seams designed to not bind when worn under your favorite work pants. Our WickWork™ technology, in combination with lighter-warmth lower leg panels and crotch, provides maximum breathability, comfort, moisture wicking, and odor resistance helping you stay dry and comfortable during active work days.