B-serie is common Inner Runner Motor for all kinds of models. It can be used directly or with a gear box to reach higher torque. GS offers Gear Boxes with different gear ratio. Besides, we have obtained the patent for two kinds of technologies of this motor, one is thread-fixing between front endplate and housing, and there other is thread-fixing between rear endplate and housing, the Patent No. is ZL2005 2 0067042.3.