DM2820 Outrunner Brushless Motor is made by high-tech material, advanced designing technique, delicate manufacturing technology and strict testing method. Its advantages are high efficiency of electro-magnetic conversion, high torque, low running noise, long working life, etc. Specification: Weight: 158g Outside diameter: 39.0mm Length: 43.4mm Spindle diameter: 5.0mm Propeller: 13x8 (optimum) RPM per Volt: 750 RPM/V a. 4 Li-Poly cells Working current:: 25A (continuous running) Rotation rate (with prop): 6500RPM b. 5 Li-Poly cells Working current : 35A (continuous running) Rotation rate (with prop): 7500RPM