100% paper straw – spf rated Sun Protective & Ventilated: Rated UPF 50+ maximum sun protection; the upf brim can also provide some sun protection during gardening. Adjustable Size – the Medium size could fit most, 55-57CM 21.6-22.4. With an adjustable drawstring built in sweatband to help find the best fit. Optional/Detachable CHIN STRAP: the neck cord is exceedingly useful for windy days, or to keep your sunhat in position while gardening, travelling, fishing, boating or hiking! Foldable & Collapsible & Crushable – you can slightly fold it and tuck in away in suitcase, great for cruise & travel, beach vacation, outdoor hiking and the like. Also it can regain its shape easily. Stylish & Lightweight: The hat looks more stylish with the fashion pu band decoration .