Innovative fabric generates heat by absorbing body moisture Moisture-wicking so you stay dry Just-right stretch so the fabric “gives” yet retains its shape Layers neatly under clothing Quarter-zip style Thumbholes at sleeves 94% polyester/6% spandex. Machine wash. Imported Lightweight for easy layering — indoors and out. If there’s one thing Wisconsin winters have taught us, it’s that staying warm starts with a good base layer. Our Thermaskin™ Heat Quarter Zip not only provides an extra bit of warmth — it’s super soft and comfortable too. The high-performance fabric actually helps generate heat by absorbing body moisture. It also wicks perspiration away from your skin, crucial for comfort in cold weather. There are even thumbholes in the sleeves so they stay put when you’re sliding into your top layer. We think of everything, don’t we?