The Splash Drone 40A ESC is optimized for SplashDrones. The circuits and functions are optimized for reliability and good heat dissipation. Designed for Splash Drones, but also a great choice for other custom drones.
OPTO means this ESC lacks of the BEC Circuit, BEC circuit is to convert the battery’s input voltage to 5V for powering the Receiver. Most of the expensive Flight Controllers (e.g. DJI NAZA) has a BEC unit included, so many players will use OPTO ESC to save money and less work load on the ESC. However, if your Flight Controller has NO BEC included, you will need to purchase an UBEC module (5V) to power up the RC Receiver.