100% Nylon Best Use: Lightweight protection from the sun, wind, and rain. Sun Protection: The fabric provides UPF 50 protection from the top of your head while the brim provides some some sun relief to the neck and shoulders. Rain Protection: the Nylon fabric is covered to repel the rain, keeping your head dry. Wind: the lines will keep the hat attached on the windiest of days. Lightweight: less fatigue for a long day on the trail or paddling down a river.