The part number is CAP ALUM POLY 680UF 20 4V SMD. This refers to a type of capacitor that uses an aluminum and polymer construction. It has a capacitance value of 680 microfarads (µF), operates at a voltage rating of 4 volts, and comes in a surface mount device (SMD) package with a resistance value of 20 milliohms. Additionally, it is designed to last for up to 2000 hours when subjected to temperatures of 105 degrees Celsius.