You like it harder and faster? Get these Spitfire Formula Four Lock-In 101D 52mm Wheels! Due to the 52mm diameter and the asymmetrical Lock-IN shape, they are the perfect all-rounder for flip tricks and can keep the speed. The hardness of 101DU promises excellent performance, especially with Grind and Slides. Thanks to the Formula Four Performance, you can rely on these roles for a long time. The used urethane is durable and can take more than a beating!