The NRS NRS H2Core Silkweight Shirt is extra lightweight, loose-fitting, soft against the skin and extremely comfortable. It wicks moisture from your body and dries quickly. Easy to wear on or off the water on hot days or as the base layer of a layering system. Silkweight shirts offer UPF 45+ sun protection for SUP, kayaking, rafting and other active water sports. The friction-free zones under the arms ensure comfortable paddling and rowing.