Professionally tested and ridden by the Spitfire Team, the Spitfire Formula Four 99D Radial Skateboard Wheels have proven to last longer, withstand more abuse, and outperform all other wheels. These wheels were designed with Formula Four Urethane to combine all desired qualities without sacrificing any attribute. The True lasting Performance Urethane is the result of a perfect combination of features, providing unmatched speed, control, flatspot resistance, smooth anti-stick slide, and high rebound for ultimate performance. This set includes 4 wheels, made with 100% true performance urethane.