1,It has best hardness.
2,it comes with additional flange bearings which make motion more smooth.
3,it comes with two pcs of 380 level motors, which provide faster speed and triple torsion force.
4,it has thickened aluminum gearbox walls, which guarantees better stability and wear resistance of bearings.
5,it comes with 3pcs of steel gears and 1pc of driving shaft brass gear.