The Patagonia Brimmer Hat is built of recycled polyester stretch ripstop that's treated with a durable water repellent finish, 40+ UPF sun protection, and a wide brim to keep light moisture and sun off. This is a mid-crown fit and is available in two sizes with a foam brim and lightweight construction to keep this hat afloat if it ends up in the river. The adjustable drawcord chin strap keeps the hat in place, even in windy conditions, and a lightweight, low-profile sweatband offers moisture and temperature management.