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. SPECIFICATION: Output : Continuous 40A, Burst 60A up to 10 secondsInput Voltage : 2-6cells lithium batteryBEC : NO BECRefresh rate of the throttle signal : at least 400MhzTiming : High or IntermediateRed Black cable length : 120mmSignal cable length : 260mmBullet Connector : 3.5mmSize : 68 x 25 x 8.7mmWeight : 26g Shipping:5-7 days Core program for multi-rotor controllers improves throttle response. Optimized software for excellent compatibility with disc-type motors. Preset settings make usage simple, highly intelligent and adaptive. Effectively reduces the crosstalk produced in signal transmission Compatible with various flight-control systems and supports a signal frequency of up to 621Hz. Better MOSFET driving effect. MOSFET with extra-low resistance brings high performance and current endurance.