The Mammut Tree Wool Thermal FL Tights combine merino wool with lyocell and elastane in a snug base layer made for consecutive days in the skin track. A waffle knit structure holds in warmth while moving sweat away from the skin, so the fabric stays dry through a long ascent. A gusseted crotch, two-seam crotch construction, and seamless side panels cut down on friction and let the legs move freely through a kick turn. What Our Gearhead(R) Experts Are Saying:"I've worn these for four days straight on a hut trip without needing to swap them out, and the merino wool never held onto smell the way a synthetic base layer would. That's the difference on a multi-day tour when packing light means one base layer has to do the work of several."