Sunday Afternoon Cruiser hat is similar to the Boonie hat. This sun hat features UPF 50 Supplex nylon construction, inner Cool Max brow sweat band, and top-of-crown mesh that keeps your head dry and comfortable. These sun hats also have a spiral stitched 3" brim that holds shape with brim-wire stiffener. Rear external sizing cord and chin strap keeps your sun hat securely on your head. Flexible, sewn in "side stays" allows the wearer to adjust the brim shape. Wash by hand. Packs flat. 50 UPF (mesh vents not rated). Hat sizing: Medium-21-22&3/4 inches, 6&3/4-7&1/4 hat size; Large-22&3/4-24 inches, 7&1/4-7& 7/8 hat size. To measure your head, circle the crown of your head with a string or dental floss (above eyebrows and ears). Use a ruler to measure the string and compare to the above chart. If in between sizes, choose the larger.