Carrera understands that buying a slot car is an investment and that we like to keep our investments looking and performing their best! Most of Carrera parts come complete, ready to pop into your car. Carrera slot cars are easily serviceable, even by youngsters and beginners in the hobby. For example, axle sets come complete - front and rear with spur gear in place. If you can operate a screwdriver, most likely you have the skills to fix most problems that might arise with a Carrera 1/24 scale car.... all you have to do is pull out the old and pop in the new and you are ready to keep racing!