Spitfire Formula Four Urethane was developed to combine all the desired properties of a performance wheel without sacrificing any one attribute at the expense of another. Formula Four's True Lasting Performance Urethane comes not from a single benefit, but from a combination of qualities and features that together produce a truly great wheel. 

101 Duro Formula Four wheels offer:

• More speed and control on all surfaces

• Unmatched flatspot resistance

• Smooth anti-stick slide

• High rebound compound

• 100% True Performance Urethane

• Spitfire's fuller, squarer 'conical' shape