Using Van as the benchmark he measures 58cm with an Intermediate Oval Head Shape which per the Shoei Helmet Size Chart puts him in a medium. In his opinion The size Medium GT-Air II Helmet delivers a true sport fit that runs pretty consistent with the Icon AirFrame Pro, HJC RPHA 11 Pro, Shoei X-12, Shoei X-14, Shoei RF-1200, Bell Star (2016 and up) in the same size (medium). When deciding if the helmet fits focus on the feel once the helmet is on more than effort required to take it off and on. The Shoei GT-Air II is a Street Helmet that best suits riders on bikes that offer more of an upright riding position in order to extract the best performance it has to offer. This helmet is a solid option for any Street Bike offering a more neutral riding position, from v-twin to sport bikes. DOT Approved. The Shoei GT-Air II Helmet uses 3 Shell Sizes. This helmet comes with a Clear Shoei CNS-1 Pinlock Ready Shield, a Pinlock EVO Insert, a Chin Curtain, a Breath Guard, and a Shoei Helmet Bag. With the innovative and highly-acclaimed GT-Air as a baseline, the all-new GT-Air II was destined for greatness from the very start. Advancements in design, functionality and performance have further evolved SHOEI s premiere full-face touring helmet, yielding even easier adaptation to the ever-changing conditions throughout your journeys. Featuring a lengthened internal sun shield for optimal sun-glare protection, all-new "first position" shield opening for advanced ventilation and defogging, enhanced aerodynamics and noise-reduction technology, and the ability to seamlessly integrate with the all-new SENA SRL2 Communication System, the GT-Air II is equipped to accommodate your every need.