The Sunday Afternoons Sun Guide Hat is perfect for the outdoor enthusiast looking to maximize their UV protection. Crafted with water repellent and stain resistant polyester sun fabric with crown ventilation that sheds moisture and allows air to circulate while providing UPF 50 sun protection. Rear sizing band for custom fit. 8" extra wide x 3 1/4" long folding clamshell brim provides ultimate sun protection and the detachable 9 1/2" neck/face cape with FloThru venting makes sure your neck and ears are covered for maximum protection. Convertible flip up crown panels allow enhanced ventilation. Packs for travel. Ponytail friendly. Sizing (Head circumference): Medium: 21.25-23.5", Large: 22.5-24".