S	M	L
51 - 55 cm	55 - 59 cm	59 - 63 cm

 

Kids' XXS	Kids' XS	Kids' S / OO	Kids' M / O
45 - 49 cm	50 - 59 cm	47 - 51 cm	51 - 56 cm

Marker has different kids' helmet molds. Use sizing that matches your product.