Intelligent Tracing Robot car chassis, of freedom, perfect for DIY subject, science education, development of hobbies and interest, educational toys . Mechanical structure is simple, 4 DC gear motors, flexible turning, -friendly chassis is stability and very easy to expand. No add- is very convenient, the entire system highly integrated. Can be used to measure distance and speed. Educational kit for beginners(kids) to get hands-on experience about Robotics & Can extend electronics system like for or etc. realizing functions of tracing, obstacle avoidance, distance testing, speed testing, wireless remote control. Size: 25 x 14cm (LxW). Wheel size: 6 x 2.7cm (Dia.xH). Motor power supply is 3V ~ 6V. All the parameter above is tested without load. Colour: Material: Plastic Package Contents: 2 x car chassis 4 x gear motor (1:48) 4 x car tires 4 x speed encoder 8 x fasteners 1 x battery box (without batteries) Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.