By merging Craft's two flagship fabrics, the Pro Zero and the Pro Cool, the Active Extreme Concept Long Sleeve Top combines the moisture wicking genius of the Pro Zero with the moisture transference of the Pro Cool. This means that as you sweat, the Zero fibers pull the moisture away from your body while the Cool fibers pull the damp to the outer layer of the shirt. Once the moisture reaches the outer layer, the weave of the Cool fiber promotes air circulation away from the skin which dries the fabric without cooling you off at the same time. The top also incorporates an antimicrobial treatment that prevents fabric odor from setting in. The base layer has been designed to regulate your body temperature in whatever zones require it. The seamless torso has an ergonomic fit, but doesn't pull uncomfortably at the underarms since the thin, lightweight fabric is also extremely elastic. It will hug, not cling to your body, and the flatlock seams succeed in making this base layer an ideal second skin.