Spitfire F4 Classics Wheels Set Pro Lance Turqoise 54m/99D Ride the fire through the streets with the Spitfire F4 Mountain Pro Classic 99a Turquoise Wheels. Formula Four Urethane lasts longer, withstands more abuse and performs superior to all other wheels. Designed to combine all the desired properties without sacrificing any one attribute at the expense of another. Manufactured using a 100% pure urethane compound, Formula Four wheels out-performed and resisted flat spots longer with less wear than all other wheels. Higher rebound for faster speeds over rough and smooth surfaces with a hard durometer for a smoother, faster ride that won't mush out over time. Designed with an exclusive anti-stick compund that gives a fast/consistent, smooth slide all the way through.