NOTE - If ordering with Integrated Clampless J&M Headset you will need a Z-Style Lower Cord (sold seperately) and shown as Related Product at bottom of page. How well your helmet fits your head is one of the most important factors in the ability of the helmet to protect your head in the event of an accident. We want to insure you receive a helmet that fits properly. Please measure the circumference of your head just above your eyebrows and choose the correct size from the Size Chart - If your head measures - 20 1/4" - 20 7/8" (X-SMALL) - 21" - 21 5/8" (SMALL) - 21 3/4" - 22 3/8" (MEDIUM) - 22 1/2" - 23 1/8" (LARGE) - 23 1/4" - 21" (X-LARGE) - 24 1/8" - 24 7/8" (XX-LARGE). To insure a high standard of quality control, no refund or exchange will be honored if the helmet is returned with it's finish scuffed or scratched, any parts missing or the Arai carton is broken or damaged.