ZAMO(4pcs) Favourite FVT LittleBee 20A-S ESC BLHeli_S OPTO 2-4S Supports Mulitshot OneShot125 Oneshot42 Multicopter Spare Parts…

FVT LittleBee 20A S ESC BLHeli_S have all the performance you would hope for and the same tiny size as the DYS BL20A. You will struggle to find a frame small enough to fit these ESCs and they will still give you plenty of headroom on a standard 250 size quad!
This ESC allows your motors to respond to throttle decreases much quicker, allowing for more stable flying, and higher response to throttle decreases.
These ESCs do not have a BEC, you will need to supply 5v power to your flight controller with a UBEC or stepdown voltage regulator.

Oneshot125
Oneshot125 is a different and faster communication protocol between the flight controller and the ESC on your quadcopter. It allows the FC to send control commands to the motor quicker, therefore in theory your multirotor should perform better.
Damped mode With the BLHELI software rapidly evolving, you can flash the lastest firmware using the 3pin connector and suitable USB adapter and now can be used via the cleanflight GUI please note you will need to be running the Betaflight firmware to connect via the cleanflight interface but this is a simple way of adjusting and tweaking the settings of your escs.
Item name: FVT LittleBee 20A-S ESC
Size: 23.5*12mm
BEC Output: No
Input Voltage: 2-4S Lipo
Weight: 4g(include Power and signal wire)
MOS: Both low and high side fets are Nfets
Continue Current: 20A, Burst Current: 25A up to 10S
Switching speed is very fast, it has dedicated driver chip
Support Damped mode, Oneshot125, Oneshot42 and Multshot
BLHeli S Bootloader & Firmware

Package included:
4pcs FVT LittleBee 20A-S ESC

Important: 
Escs must be calibrated throttle range before using, like the video example shows, Or it will not work or Synchronize:  https://www.youtube.com/watch?v=OOplk52R4no