Warm, dry and comfortable. Altitude Base Layer grants your 3 wishes. Run mile after mile regardless of the weather with a garment that keeps the warm air closest to your body and keeps you dry. Wool blended yarn keeps the air warm and removes sweat quickly to keep you dry. Extra long silhouette with hidden elastic thumb loops to easily pull on another layer. Flatlocks seams. Mesh panels under the arms and on the back provide extra ventilation.