Siggi Womens Summer Flap Cover Cap Cotton UPF 50+ Sun Shade Hat with Neck Cord 3 Size Options: Best fit for 55-59cm 21.6"-23.2" 6 7/8 - 7 3/8. SPF 50+: this sun hat has passed UPF 50+ test, it could block 97.5% or more of sun UV rays. 4.7" BRIM: wide and long enough to shade forehead, eyes and cheeks from sun uv ray. LIGHT & VENTILATED: cool and comfortable for summer. The chin cord will keep it stay safe on head in wind. Crushable & Packable - you can easily fold it and tuck in away in suitcase, great for cruise, outdoor trip, beach vacation and the like. Also it can regain its shape easily, but sometimes you might need steam/ironing machine to reshape it.