Why moms are raving about our Kids Cotton Floppy Sun Hat? Gro-With-Me®: Drawstring head adjustment & adjustable chinstrap ensure perfect fit and longer use Superior Sun Protection: 50+ UPF breathable cotton and wide brim strengthened to stay up in front. Stay-on: Chin-strap ensures hat stays put when windy or child pulls Safe: Break-away safety clip on the chin-strap Pack-able: Light weight and easily foldable to fit in a pocket for easy storage and travel Cotton Floppy Hat Sizing: S: 0 – 6 months, head up to 45cm (17.5″) with 5.0 cm wide brim M: 6 – 24 months, head up to 50cm (19.5″) with 6.0 cm wide brim L: 2 – 5 years, head up to 53cm (21″) with 6.5 cm wide brim XL: 5 – 12 years, head up to 56cm (22″) with 7.0 cm wide brim