These winter-training superheroes have the power to keep us warm without bulk, the power to wick us dry, the power to stay odor-free, the power to stay itch-free, right next-to-skin, all workout and all winter long. That's the power of Smartwool mid-weight Merino. Heavyweight first layer or lightweight mid-layer—you choose. Washable, dryable and oh-so-wearable. XS(2), S(4-6), M(8-10), L(12-14), XL(16).