In the water or on land, this junior boys' rashguard from The North Face is ready for every fun-filled day ahead. The Amphibious Long Sleeve Sun Top is designed with moisture-managing FlashDry-XD fabric technology and UPF 40+ sun protection. FlashDry-XD materials offer enhanced moisture management to help keep you comfortable and increased abrasion resistance for extra durability. UPF 40+ Ultraviolet Protection Factor is a measure of the percentage of ultraviolet sunlight that reaches your skin. The Skin Cancer Foundation recommends a rating of UPF 30 or higher. This fabric allows only 1/40th of the sun's UV rays to pass through.