Made of 100% waterproof nylon, Rain Hats conveniently pop open for 15 inch brim of instant head and neck coverage when you need it. When not needed, twist and fold the rain hat into a 6 inch disk (with matching pouch) and place in your coat pocket or glove compartment of your car. Less cumbersome than an umbrella for those "not-sure-if-it-will-rain" days. Rain hats are uni-sex. Hats are one size fits most. About hat sizes.