Must with::H45157 Motor Pinion Helical Gear 12T. New style high strength 121 tooth Mod 0.6 helical main hear for 450 size helis. The increase gear pitch can withstand higher power, at the same time minimize operational noise. A great upgrade to withstand the modern high power system. Utilizes high strength polymer plastic with excellent rigidity and flexibility characteristics. Patented unique built in fan design to create induced air flow, effectively cooling electronics and motor. Gear ratio 1:10.08.