YKS 4Pcs Simonk 20AMP 20A SimonK Firmware Brushless ESC w/ 3A 5V BEC for DJI F450 Align TREX 250 RC Multicopter Qudcopter Helicopter ESC Part (4 PCS) SimonK firmware gives you the perfect solution for multirotor use.Highest efficiency 100% N-FET design. Highest accuracy with Crystal Oscillator (temperature won't affect the PWM operating range like other cheap ESC's). No over temp cutoff, because any cutoff in a multirotor = crash.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.