YKS 2-4S 30AMP SimonK Firmwar Brushless ESC Speed Controller w/ 3A 5V BEC for DJI Phantom RC Quadcopter ESC Part (Pack of 4) Output: Continuous 30A, Burst 40A up to 10 Secs. The applicable number of battery cells: 2-4S Highest efficiency 100% N-FET design and highest accuracy with Crystal Oscillator. (Temperature won't affect the PWM operating range like other cheap ESC's). Ultra 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).