Hobbywing SkyWalker-40A Brushless ESC Electric Speed Controller with BEC Safety arming feature: Regardless the throttle stick position, the motor will not spin after battery connected. Throttle calibration funtion: Throttle range can be calibrated to be compatible with different transmitters. User programmable.Compatible with Lipo and NiMH battery.Timing can be changed to be suitable for different brushless motors. Multiple program methods supported: transmitter stick, LED Program Card. Very easy to program the ESC at home or at the flying field. Full protection: Low voltage cutoff protection / Over-heat protection / Throttle signal loss protection.