When we're headed out on fast-paced winter adventures we want a garment that breathes exceptionally well while still providing warmth. So we came up with the Lightweight Merino Baselayer Crew. We brought the thermoregulating and odor-resistant performance of merino wool together with the durability and moisture-wicking performance of nylon--with a touch of spandex for stretch where you want it--to handle our most demanding days in the mountains.