The Arai Difference: It's The One You Can See, Feel, Touch. And Trust. The simple truth is, while there are a lot of helmets out there, there is still only one Arai. Their name and reputation have been forged over time, the hard way. Which means they haven't devoted three generations of the Arai family to the singular goal of no-holds-barred excellence just to turn out helmets like everybody else's. Arai alone has the experience, the quality, and the trust that truly set them apart. Optional interior comfort headliner pad for the Arai XD4 and VX-PRO4 helmet. Sizing: Size I: For XS helmets. Size II: For SM helmets. Size III: For MD and LG helmets. Size IV: For XL helmets.