Specification:

Chips on EFM8BB21.-BLHeli_Sis designed for superior performance in multirotors, and uses hardware generated motor pwm for smooth throttle response and silent operation.                 
Small size combined with light weightfor easy installation.- The code supports regular 1-2ms pulse width input, as well asOneshot125 (125-250us), Oneshot42 (41.7-83.3us) and Multishot (5-25us).  The code supports features to prevent sync loss. There are tuneable parameters that can make the code run well even in the most demanding situations, although default settings will work-excellently in normal operating environments.                                                  

4 * DLFPV   BLHeli_S 30A ESC OPTO Electronic Speed Controller 3-6S Brushless for FPV Multicopter Quadcopter