The descendant of the first technical base layer created in 1984, ME Chamois has developed a reputation for being the most reliable, durable underlayer made by our company. The secret to the success of this men's thermal long sleeve lies in the fabric's intimate blend of enhanced polyester and spandex fibers. Our unique recipe for this thermal base layer top calls for exceptional stretch-ability in a polyester treated with anti-microbial properties that inhibit the growth of odor-causing bacteria. The result is a highly technical, high-performing men's thermal base layer top that'll keep you warm for years to come. Fit Tip - The Micro Elite Chamois products feature a snug, body fitting silhouette for exceptional moisture management. If you are in-between sizes - order up one size. Contrast flat seam construction Seams set away from shoulder for added comfort Smooth face for easy layering Napped back for extra warmth and softness Thumbholes Moisture Transfer Fibers to move moisture away from skin 4-way stretch for unlimited movement UPF 30 protection Midweight warmth, body fit