Often there are multiple power plugs in one location which should only be mated with the correct power supply. The sealed power plug is available in multiple pin diameters as well as with color coded tip insulator rings to prevent incorrect mating. Having multiple center pin diameters helps prevent mating of a 2.5mm center pin plug into a 2.0mm jack, not allowing incorrect mating by the user. Additionally the color coding on the tip insulator ring makes it possible for the operator to visually identify the size of the plug.