NRS H2Core Lightweight Zip Neck LS Shirt - Men's Casual zip-neck design for easy on/off and quick ventilation Versatile 9 oz technical fabric combines comfort and breathability with just enough warmth to take the chill off on cooler days Friction-free zones under the arms ensure comfortable paddling and rowing Lightweight fabric also provides advanced sun protection for SUP, kayaking, rafting and other active water sports UPF 50+