Worn on its own, it keeps you dry and cool during high-exertion activities in warm conditions. Worn under a shell when a chill wind blows, it wicks perspiration and helps to insulate. Details include a deep zipper to vent the full-coverage neck, raglan sleeves that won't chafe under pack straps, and side seams that roll forward for smooth layering. Made with 4-oz 100% polyester (54% recycled) with Gladiodor® odor control for the garment. Recyclable through the Common Threads Recycling Program.