Unless you"re down with melanoma, it"s probably a good idea to put on the Reef Rashie SS Men"s Rashguard. It has 50 UPF-rated protection to block out harsh UV rays when the sun is high, and it"s woven with elastane so it doesn"t inhibit movement when you"re paddling and surfing. Product FeaturesMaterial: 92% nylon, 8% elastaneInsulation: Built-In Bra: UPF Rating: 50Recommended Use: surfingManufacturer Warranty: 30 days