Description 5.5 x 2.1mm DC barrel jacks are one of the most popular connectors used on consumer electronics. These connectors are specifically used in low voltage situations; you probably have a drawer of old power supplies with these laying around! This adapter is designed to save you from hacking the end off a cable just to make a temporary connection. The connector fits any standard 5.5 x 2.1mm DC barrel plug and breaks it out to a labeled set of screw terminals. We also have the mating connector available with this screw terminal breakout.