Smart car chassis tracing car Robot car chassis with code disk, Ideal for DIY. This car is the tachometer encoder. With a 4 AA battery box (batteries not included). Can be used for distance measurement, velocity. Can use with other devices to realize function of tracing, obstacle avoidance, distance testing, speed testing, wireless remote control. Size: 21 x 15 cm (L x W). Wheel size: 6.5 x 2.7cm (Dia. x H).
