Upgrade your baselayers to something warm, luxurious, and made of natural fibers with the Smartwool Classic Thermal Merino Base Layer Bottoms. A slim fit with an elastic waistband keeps the fit dialed, with a next-to-skin feel and breathability that only merino wool can provide. Flatlock seams and an interlock knit keep everything cozy and chafe-free so you can focus on your adventure in the mountains and beyond.