Spitfire F4 101a Tablets 53mm Natural/Red Spitfire Wheels $ 38.00 Default Title - $ 38.00 Quantity This product is currently sold out. Please fill in the form below if you'd like to be notified when it becomes available. Spitfire's premium formula four urethane in a tablet shape Formula Four Urethane - Resists Flatspotting 53mm Wheel Set of 4. 101a Durometer Tablet Shape