The Arc'teryx Rho AR Top is an excellent mid-layer for aerobic activities or an equally great expedition weight choice for insulation in cold winter sports. It is form fitting and features Polartec Power Stretch, which wicks moisture and prevents constriction. Arc'teryx Rho AR Top Features: Moisture-wickingInsulatedGreat warmth-to-weight ratioLaminated sleeve pocket with laminated zipCollar zip for improved ventingMaterials: Polartec Power Stretch