When you want to power up (connecting it to the electricity network, like the one at home) a cooled camera, a computerized mount, or another accessory you need a stabilized DC power to supply the necessary current. This stabilized 12V 5A power supply has a 5.5mm (outer diameter) - 2.1mm (inner diameter) plug with central positive pole so it can be connected directly to the power port of most computerized mount, cooled cameras or other accessories.