● 100%cotton. ● SIZE - Small best fits for 55-56.5CM 21.6"-22.2"; Medium best fits for 56-58.5CM 22"-23"; Large best fits for 59-61CM 23.2"-24". ● 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 97.5% or more of sun UV rays. Great ventilated to keep you cool in summer. ● WIDE BRIM: measures 4"-4.7" in length, is large enough to shade forehead, neck and cheeks from sun lights. ● Ponytail Hole - great to pull your bun or ponytail through during summer days.