Arai Signet is the true Long Oval shape... I just went through this process earlier this year. I must have tried on 15+ different helmets at the IMS show, was measured the the Arai guy, Shoei rep ect.... Arai dealer could spot my oval head from 20' away. The Signet wasn't cheap but if you have the Long Oval head.. your options are limited. I was really hoping to get a Scorpion helmet to fit properly.