GoolRC 4Pcs Simonk 30AMP 30A SimonK Firmware Brushless ESC w/ 3A 5V BEC For DJI F450 Align TREX 250 450 RC Multicopter Qudcopter Helicopter ESC Part 30A ESC for multirotor Highest efficiency 100% N-FET design Super high refresh rate, no buffering of the input signal, resulting in more than 490Hz response rate 16KHz motor frequency, giving fastest response of the motor, and quietest operation as well (no 8KHz squeal) Super simple, foolproof operation! Nothing to program other than the throttle range