Use this adapter to connect a DC Female 2.1mm jack to a power supply that comes from wires. This adapter has a 2.1mm DC male barrel-type plug on one side, and screw terminals on the other, useful to power-up devices from batteries or professional DC power supplies.

The adapter has labels for positive and negative connections on the terminals, and has positive-center configuration. Works well with Arduinos and development board with a 2.1mm female jack.