Add more vehicles to up the suspense and create an epic collision in one of three crash zones. One Hot Wheels® vehicle is included; additional cars sold separately. The earliest boosters, the Super-Charger and 2-Lane Super-Charger from 1970, were powered by 3 "D"-sized batteries and featured a lever on the side for "Speed Shift Control". More recent boosters use 2 "D"-sized batteries and are smaller in profile, and usually do not feature any sort of speed control. Early boosters use foam wheels; most modern boosters use rubber wheels due to the fragility of the foam which has a tendency to wear down over time through continued use. Models without fender protection are not recommended for use in boosters as the booster wheels rotate with sufficient force to bend the axles. legendary Hot Wheels cars: Rip Rod™, Surf 'N Turf™, Bone Shaker™, Twin Mill™ III, Donut Drifter™, Hotweiler™ and Loco Punk™. Makes a great gift for kids 5 years old and older who love crashing and smashing action with their Hot Wheels®. The Power Booster Kit includes 35+ pieces including 2 speed loops and two boosters so you can boost your crash, your loops and head-to-head races! ?