Kuhl Men's Stealth Shortsleeve Shirt is a casual shirt is actually quite technical. It's woven from a nylon microfiber with dull yarns for a luxurious soft hand. UPF 30. Negativly charged silver ions help prevent the growth of bacteria. And keeps heat away from the skin to help you stay cool. The Stealth also features a hidden pocket to secure you passport or slim wallet and often secured by a micro-zipper, peace of mind for world travel.