WOW Motorcycle Full Face Helmet Street Bike BMX MX Youth Kids Shark Blue; Size S (49-50 cm 18.9/19.3 Inch);

Helmet Size Chart

S 49-50 CM 18.9/19.3 Inch
M 51-52 CM 19.7/20.3 Inch
L 53-54 CM 20.7/21.1 Inch
Helmet Size Tips

(1)Wrap a measuring tape around your head about a half-inch above eyebrows
(2)Take measurement two to three times to pick the largest one.