GAST Air Gear Motor  1UP-NRV (GM) Series, imported from America, small size, compact, can adjust the speed. Which can reduce the speed up to 15: 1, resulting in reducing the speed But increase the torque to be higher In addition, it does not cause sparks. Able to work in flammable areas. There are 2 types of propellers, 4 propellers and 8 propellers. The working direction of the propellers is from Counter-clockwise, clockwise and bi-directional rotation etc.