The Phoenix Edge 50 ESC from Castle Creations is an excellent addition to your RC helicopter or fixed wing model. This 120V ESC has a maximum continuous current of 120 amps. Similar to the other Phoenix Edge ESCs, this speed controller features an auxiliary wire which you can be easily programmed. This white auxiliary wire can be used for a wide variety of functions. For example, you can use it to adjust the helicopter governor gain mid-flight. It can serve as an audible beacon in the event of an unexpected landing. If you have a 3-axis gyro that supports RPM sensors, the wire can act as an RPM output. Additionally, it can be used as an arming lock for your ESC (Castle Creations have included a coupon for a free Arming Lockout Key with the Phoenix Edge 120). Furthermore, the wire can be used as a receiver arming lock.