Capacitor CAP ALUM POLY 390UF is a type of aluminum-polymer capacitor with the following specifications: capacitance of 20 microfarads, voltage rating of 2.5 volts, surface mount design (SMD), and a size classification of 2917 or 7343 metric, which corresponds to a 9 milliohm ESR value, as well as an operational lifespan of approximately 5500 hours at a temperature of 125 degrees Celsius.