The Chiller Long-Sleeve Shirt is the coolest hiking shirt on the planet! Mountain Hardwear's exclusive Cool.Q ZERO advanced cooling technology accelerates the wicking process and helps your body minimize heat and maximize energy. Ultra-durable 86% polyester, 14% elastane Flex Stretch fabric resists wrinkles, dries quickly, and offers built-in UPF 40 sun protection to shield your skin against harmful rays. The shirt's seams are rotated away from pressure points for premium comfort even when wearing a pack. The sleeves roll up and secure at the side button tabs for quick fit adjustments in changing conditions. The Chiller Long-Sleeve Shirt features a flip-up sun collar for added UV protection; a buttoned front placket for secure closure; and a zippered Napoleon chest pocket for convenient storage. Standard fit. Imported.