D2-5 Smart Tracking Robot Car Sets: PCB size: 73x105mm, powered by 3V DC (batteries not included). Intelligent Design: Uses light reflection to differentiate between black and white surfaces, allowing the smart car to follow the correct path automatically. The car can freely travel along a black tracking line by identifying the direction autonomously. Customizable Track: Design complex tracks directly on the ground using 1.5~2.0 cm black electrical tape for added fun and challenge. Easy Assembly: Clearly marked and illustrated connections on the board make assembly straightforward. Requires basic electronic theory knowledge and welding skills. Wide Application: Great for students, electronics enthusiasts, and DIY hobbyists. Ideal for science fairs, learning basic mechanical and electronic skills, practicing welding, and enjoying the process of building and learning., Manufacturer: The Lord of the Tools