This is a general purpose power supply filter capacitor for RC systems. Usually plugged directly into a spare receiver channel on 5 volt systems, it helps protect against noise and brown-outs on the power supply.
Servos generate noise and can cause momentary voltage dips (brown-outs) on the 5V power supply. Too much noise or too large a voltage dip, even if only for a fraction of a second can cause sensitive receivers to reset or briefly loose bind.
This capacitor is only suitable for systems operating up to and including 5 Volts DC; most systems.
The leads are crimped and soldered for a secure connection and heat-shrink covered. The capacitor should be secured against vibration.
Some capacitors have a servo-wire lead between the plug and the capacitor. This can be convenient but is not a good idea. The shorter and heavier the connection, the better it will work due to the lower impedance. Basically, the more effectively the capacitor can accept and deliver current to smooth out the unwanted voltage variations.