mmg ytz7s lithium ion sealed powersports battery 12v powerful 150cca, no spills, factory activated, ready to use for motorcycles scooters atvs (mmg3) mmg <b> motorcycle scooter open face helmet</b> <br> <br> size chart <br> - small: 21.7 – 22 in / 55-56 cm <br> - medium: 22.4 – 22.8 in / 57-58 cm <br> - large: 23.2 – 23.6 in / 59-60 cm <br> - xl: 24 – 24.4 in / 61-62 cm <br> - xxl: 24.8 – 25.2 in / 63-64 cm *some variance occurs, even between different models from the same manufacturer, which is why we offer a "no questions asked" return program. if your helmet does not fit properly, just send the helmet back to us for a full refund.