Real race cars use bearings to reduce the speed-robbing friction between moving parts. Pinewood racers don't. When the axles roll against their slots, drag is created that slows down your wheels. What can you do? Just use Pinewood Derby®'s high-quality polishing system to make the axles as smooth as possible — and put the maximum "glide into your ride". Includes: One sheet of 600-grit sandpaper and one 2-ounce bag of pumice. Age: 8+