Here is a Measuring Chart to help you find the right measurements. Lightweight low-profile helmets from Ovation®! Helmet features rubberized finish, easy adjust dial for a snug fit, extra strong adjustment teeth for added helmet life, high flow vents to keep you cool, removable washable liner, removable breakaway visors and exclusive YKK® adjuster clip and buckle, positioned to stay off of the rider's face for comfort. SEI certified to ASTM F1163-04A & CE certified to European EN 1384 Standards.
Here is a Measuring Chart to help you find the right measurements
18 3/8" TO
19 1/4" TO
20 3/4" TO
22 3/4" TO