The Summit Pro Baselayer Tight blends recycled polyester with wool in a DOTKNIT construction built to move moisture away from the body during real cold-weather output. FLASHDRY Pro technology adds enhanced moisture management on top of the wool's natural odor resistance, so the fabric keeps working across long days instead of just the first hour. Flat-locked seams and inseam gussets let the tight move with the body rather than against it. What Our Gearhead(R) Experts Are Saying:"I wore these for three straight days on a hut trip without a wash, and they never got that sour smell synthetic baselayers get by day two. The wool blend does real work there, not just the moisture-wicking."