105mm (length)，90mm (width), 117mm (height). After the assembling is done, the car can achieve track driving and excellent off-road performance. In addition, the car can be switched between two-wheel-drive and all-wheel-drive modes. During the assembling process, students can not only grab the speed-down theory and the definition of transmission ratio, but also learn some tips for wiring. In this way, they will have enhanced operational ability and creativity as well as strengthened team-work spirit.