THERMAL MIDWEIGHT BASE LAYER FOR MEN - Your go-to for a classic men's midweight base layer, Micro-Elite Chamois is the descendant of the first technical under layer created in; this fabric has developed a reputation for being the most reliable, durable long underwear made by Hot Chillys HIGHLY TECHNICAL, HIGH-PERFORMING MEN'S BASE LAYER - The secret to this thermal underlayer's success lies in the fabric's intimate blend of enhanced polyester and spandex fibers; micro-Elite Chamois Zone Zip-T is a highly technical, high-performing piece of base layer that'll keep you warm for years to come MOISTURE TRANSFER FIBERS - Micro-Elite Chamois is designed with wicking capabilities: moisture transfer fibers to wick away moisture from your skin; this durable warm long sleeve base layer features comfort active stretch seam construction and smell blocking properties to keep you comfortable and cool WARMTH & COMFORT - Warmth factor 8 out of 10 - Smooth fabric outside, lightly brushed inside for exceptional warmth in cold conditions; this Zip-T base layer with thumbholes features seams set away from shoulder for added support; it incorporates zip through collar with interior wind flap for ultimate warmth BODY FIT DESIGN - Featuring zoned panel placement that follows the contours of the body, this crewneck base layer will keep you warm without restricting movement; 4-way stretch for unlimited movement; it is designed to move with you, allowing full range of motion while staying against your skin