Men's Anatomica Leggings with Fly XL - Black. Ultra light base layer bottoms built with a super-soft, stretchy and highly durable merino wool blend, the Anatomica Leggings w/ Fly provide the breathable insulation you need for cool-weather pursuits on the trail or in the backcountry. With an updated fit that makes them even more comfortable, the Anatomica Leggings also feature our corespun fabric, which uses nylon fibers wrapped in merino wool for increased durability and strength that retains next-to-skin softness. Flatlock seams eliminate chafing when you’re hiking, skiing or climbing, and the contoured pouch with fly offers additional support and function.