All Banz sunglasses have tough UV400 polycarbonate lenses, which have been clinically tested and are proven to give 100% protection from the sun's harsh UVA and UVB rays. Baby Banz fit children up to two years or a head circumference of up to 43cm. Kidz Banz fit children of two to five years, or a head circumference of 43cm to 53.5cm.