The ThunderJet Ultra G chassis is Auto World's adaptation of the classic "pancake" slot car motor design, originally developed by Aurora in the early days of electric slot racing. Still immensely popular today, entire slot racing events are created around this chassis. It continues to be a favorite with collectors and hardcore drivers. Closer to HO scale, ThunderJet bodies mount over the chassis using two small screws. ThunderJets are retro slot car racing at its best!