Introducing the newest wheel to be released from Spitfire. The Spitfire Formula Four in either 101Duro (street) or 99 Duro (park). Spitfire Fire got there team members to test the Formula Four wheels and the results show that the Formula fours withstood more abuse and performed superior to all other wheels. The Spitfire Formula Four Urethane was made to withstand flat spotting and withstand heaving skate sessions without wearing down. The Formula fours are truly like no other wheel we have seen before.