SIZE - Small fits for 54-56CM 21.2"-22"; Medium fits for 56-58CM 22"-22.8"; Large fits for 58-60CM 22.8"-23.6". With an adjustable drawstring built in sweatband to help find the best fit. FOLDABLE: folds up easily, compact and perfect as a fishing or travel hats. DETACHABLE CHIN STRAP: adjustable for a better fit; won't blown off when it gets windy. SPF 50: this sun hat has passed UPF 50 test, it could block most sun UV rays. WIDE BRIM: measures 4 - 4.5" in length, large enough to shade forehead, eyes and cheeks from sun uv ray. The shape looks really adorable.