Designed to keep you warm and wick away moisture, the REI lightweight base layer half-zip top is ideal for high-performance outdoor activities when the temperature starts to drop. Features: - Made of a soft polyester that wicks sweat and dries fast - Tall neck extends coverage; zipper with chin guard lets you adjust ventilation - Flatseam construction, raglan sleeves and side gussets are comfortable as you move - Longer back hem stays tucked when you stretch