Kids sun hat is made of premium 100% polyester,so it is breathable, quick-drying,lightweight and comfortable wear Sun Protection: This baby boy sun hat is wide enough to provide your child with excellent sun protection, protecting the child's head, eyes, face and neck from harmful sun UV rays, which means more time for outdoor activities. Adjustable chin cord keep your hat safety in windy day, hat with drawstring at back for flexibility Moisture wicking sweatband, wide brim hat with mesh airflow vents for comfortable wear Please match with the actual Circumference before purchasing.Size S: 18.9"-19.7" (48-50cm), suggested to 6-24 months, Size M: 19.7"-20.5"(50-52cm), suggested to 2-5 Years 111