This hat is size Medium fits 22.5" head or hat size 7-1/8th. It has an approximate 3.5" brim. It is hand woven palm with a cotton blend sweatband and UPF 50+. Tula Hats were tested at the Textiles Laboratory at California Polytechnic State University and came back with glowing reviews. Our hats were tested specifically with the intention of finding out their UV transmittance rate. They scored UPF 50+ (a zero UV transmittance score!)