Hobbypower SimonK 30A ESC Brushless Speed Controller BEC 2A for Quadcopter F450 550(Pack of 4) For sale is 4pcs 30A SimonK firmware Brushless ESC. Soldered with 3pcs 3.5mm gold female plug, very convenient to connect motor. 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 low voltage cutoff, because any cutoff in a multirotor = crashNo 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.