Different types of trails call for different layers.Our lightest mid layer, made with over 90% recycled polyester, is designed for complete comfort when heading out on the cooler days.The special waffle grid looped backside structure provides thermal comfort and helps wick away sweat from skin.The longer backside makes it backpack-compatible without riding up and the close fits sits under other layers without impacting your movement. Compare prices from: Adidas in Men's Clothing