Features: 1) Auto-rotation system 2) Rear tail servo mount 3) Collective pitch system 4) Tail rotor drive belt system 5) Main drive gear with cooling fan 6) 35 precision bearings Specifications: 1) Length: 650mm 2) Height: 230mm 3) Main rotor: 680 / 700mm 4) Tail rotor: 150mm 5) Motor gear: 15T / 13T / 11T 6) Main gear: 150T 7) Autorotation tail drive gear: 109T 8) Tail drive gear: 22T 9) Drive gear ratio: 1:10:4.95 / 1:11.5:4.95 / 1:13.6:4.95 10) Weight (without power system): 325 / 345g 11) Weight (including power system): about 610 - 650g