When a foot-wide ledge becomes your bed for the night, this compressible zip-neck helps turn up the heat. The micro-grid fleece interior of our Capilene Thermal Weight provides the greatest warmth combined with the greatest breathability of any baselayer in our lineup. Soft, stretchy and compressible, Polartec Power Grid fabric has a smooth face that glides beneath layers and a brushed fleece interior to warm your core, wick moisture and feel smooth against your skin. This fabric also has 30-92% recycled content and is treated with Polygiene permanent odor control. Product features include a self-fabric backing on the collar that provides added comfort and a locker loop that lets you hang it to dry, a long center-front zipper for venting, full underarm gussets for unhindered shoulder mobility, elastic thumb loops to help cover your hands, flatlock seams that minimize chafing, offset shoulder and side seams that lie smoothly beneath pack straps, and a drop tail for additional coverage.