For customers' requirement, we develope this 4WD smart car chassis. It can be use with modules to achieve tracking, obstacle avoidance and so on. Holes on the car chassis are not suitable for every modules. But you can install your own hole, this is acrylic materials, it is easy to punch. But be careful of break the board. How to turn: There are 4 motors. The left / right two motors should be in parallel. When turning left, the left two forward and right two back. Conversely to turn right. Can 7.2V or 12V be used: Of cause! But do not connect to the motors directly. You need to use the motor drive module programming PWM to control speed. Can this car chassis achieve speed or distance measuring: If you want to achieve these two function, you need to buy encoder and speed or distance measuring module. Specification: Model: ST-4WD Working voltage: 9V Material: acrylic Chassis size: 230 x 120 x 5mm Wheel color: black and yellow Package included: 1 x Chassis 4 x TT motor 4 x Wheels All necessary screw and nut.