Spitfire F4 Conical Full 52mm 101a Skateboard Wheels the prime urethane formula wheel by Spitfire. Tested by Spitfire Team riders, Formula Four Performance Urethane lasted longer, withstood more abuse and performed superior to all other wheels.

Bearing core -  Center-Set so you can reverse the wheel to save the graphic and help get longer life out of your wheels as you can rotated them so they burn down evenly. 

Wheel Shape / Profile: Conical Full - Conical refers to the cone shape produced by using flatter surfaces from the contact patch to the side of the wheel. Double Conical wheels were a popular shape in the late 1970’s. It either referred to a conical shape being used on the corner & from the wheel side to the bearing seat or a conical profile on both sides of the wheel. In recent years this shape has been modified to suit smaller hard wheels. It provides a nice shaped corner for slides, flatter wheel sides to lock into edges and wider contact patch. The Conical Full is around 2 to 3mm wider than it’s straight conical partner if you are looking for a little more grip and slide control over speed.For more info read Spitfire Wheel Shapes Explained

Urethane - Formula Four 101a: Spitfire released their new Formula Four wheels a few years ago now. The latest formula was designed for higher abrasion resistance. This means it is a little harder to flat spot. Usually adorned with a red coloured graphic, the Formula Four 101A wheels are the hardest Spitfire Wheels available. They are super fast on smooth surfaces and the easiest to slide. Being super hard, if you find they let go on smooth surfaces or feel unpleasant on rougher terrain, switch back to the 99A models. There are no hard and fast rules, best to try out different wheels and select what works best for you. For more info read Spitfire Wheel Formulas Explained