Siggi Womens Bucket Boonie Sun Hat Summer Cap Packable Wide Brim UV SPF 50 Pink FREE SIZE: with an adjustable tape at back built-in sweatband. Best fit for 55-58cm 21.6"-22.8" 6 7/8 - 7 1/4. 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. UPF 50+: this sun hat has passed UPF 50+ test, it could block 97.5% or more of sun UV rays. WIDE BRIM: measures around 4" in length, large enough to shade forehead, eyes and cheeks from sun uv ray. The shape looks really adorable.