Lean In Caps Baby Boys Car Styling Baseball Cap Style: Baseball cap Material: Cotton Hat circumference sizeS:18.1 Inch(46 cm) (fit about 6-12 Months); M:18.9 Inch(48 cm) (fit about 1-2 Years); L:19.7 Inch(50 cm) (fit about 3-4 Years); XL:20.5 Inch(52 cm) (fit about 5-6 Years) It can be use for the sun protection,keeps your baby's head nice and warm, it can be worn all the year round. It can be adjusted in the back,the hat is beautiful, amazing quality,very durable,bendable,so washing and packing/portability are easy.