Yes, you know Smartwool socks, but do you know Smartwool's base layers? This version of Smartwool's key layer top is done a very fine merino wool blend, providing lightweight warmth when there's a nip in the air. The top has long sleeves and a flatlock seam construction that helps prevent chafing; the fit is quite close. Merino wool naturally helps regulate body temperature, transports sweat away and cancels out odors. The plant-based dye adds an eco-friendly element to the look. 

• Our model, Katie, is 5'10". She's wearing a size XSmall here, which fit nicely. Her measurements: Bust, 34 inches; Waist, 26 inches; Hip, 38 inches.
• 88 percent wool, 12 percent nylon.
• Machine wash, cold, gentle cycle; lay flat to dry.