This 4 wd double-layer smart car chassis. It comes with the two pairs of Geared Motors and Wheels. All the products included in this car kit are quality products. The chassis used in this kit is transparent to create dynamic handling of the components mounted on your robotic vehicle.
 
Specifications:
For BO Motor:
Operating Voltage: 3V~12V DC depending on the driver 
Gear Ratio 1:48
No-load speed(5V): about 208RPM
Rated Torque: 0.8 Kg.cm @ 5V
Load current: 170mA (when it is 4.5V)
Size: 70 x 23  x 18 mm
Weight:28g
Shaft Length: 10 mm
Shaft Type: 6 mm, Double-D