AER Splash™ water repellent technology keeps your hat from getting water logged. The water beads up and runs right off the hat, almost like magic! HyperPoly+™ fabric for heightened sweat stain prevention (no white sweat lines) Hidden AER Run Pocket! Store a key or fuel right inside your hat (select styles) Ultra lightweight; light as a feather fabric Extreme sweat wicking material to take on your toughest runs/adventures Maximum durability for longer lasting colors (stays fresh as the day you got it!) Low maintenance care. Wear, sweat, hand rinse cold (only), REPEAT! No washing machine required to stay fresh!