evo.com | Smartwool Long Underwear Bottoms > 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. 100% Merino Wool Made with an interlock knit for enhanced comfort, breathability, thermoregulation, and odor resistance. Interlock Knit Slim Fit Fabric Weight | Mid 250 Single layer for cold weather performance. Baselayer for very cold weather. Flatlock Seam Construction Designed to Eliminate Chafing | Women's Smartwool Classic Thermal Base Layer Bottoms 2026 - Large Gray