A 16 mm wide black runway is located in the white field. The tracking car can automatically follow the black runway regardless of how it is curved. Using a red light source, the system detects reflectivity differences between white and black surfaces. Light reflects from the surface to a photoresistor, and changes in resistance indicate whether the car is on the white area or over the black runway. When the black runway is detected, the car adjusts its direction, controls the motor, or stops accordingly, and the red LED on the front side of the PCB turns off. This ensures the car continuously follows the runway. Model: D2-5 Name: D2-5 Intelligent Tracking Car DIY Kit PCB Size: 104x72x1.6mm Installation Dimension: 104x72x55mm Operating Voltage: 3V Color: Blue Material: Plastic + Metal Note: Soldering is required for assembly; 2 AA batteries are not included. Package Contents: 1 x DIY Electronic Kit The package includes only the items listed above. Other accessories are not included. Note: Differences in lighting conditions and display settings may cause slight variations in color between the product image and the actual item. Measurement tolerances are +/- 1-3 cm.