The Outdoor Research Helios Sun Hat is broad-brimmed to protect you from intense sun rays with a SPF 50 rating. To keep sweat out of your eyes the moisture absorbing headband moves moisture away from your brow, and the brim offers protection to your face and neck with a wide swath of shade. The external drawcord and removable chin strap adjustment keeps it on your head even in windy conditions. Should the hat get blown off when you are on the boat or at the beach or casting a fly on the local creek Outdoor Research added foam to the brim of the Helios not only for shape but also to allow it to float.