TOOGOO(R) Original ZTW Spider Series 40A OPTO Brushless Speed Control ESC 2-6S Lipo for DJI Flame Wheel F450 F550 Multicopter Quadcopter Helicopter Airplane Part 1.Extremely low internal resistance 2.Super smooth and accurate throttle linearity 3.Safety thermal over-load protection 4.Auto throttle shut down in signal lose situation 5.Supports high RPM motors