- EXTREME WATERPROOF UPF50+ FABRIC: This baseball cap is made of 100% premium polyester technological fabric which waterproof capacity >200kpa, effectively prevent water molecules from entering, to ensure your outdoor sports carefree. Rain hats can also be used as sun hats, with UPF50+ effectively blocking more than 99% of UV rays. Protect your eyes and face. It's your perfect outdoor hat, rain hat, sports hat, golf hat