The PoE injector adapter on the cable is a splitter that allows you to power devices via an Ethernet cable. It is used when the remote device supports PoE supply via the Ethernet socket. The splitter has an input for connecting the power supply, an Ethernet plug for connecting to a LAN and an ethernet socket to which remote devices can be connected. The power socket has a diameter of 5.5 mm and a pin with a diameter of 2.5 mm. If you need to supply voltage to a remote device that does not support PoE, you probably need: [Injector PoE], with 5.5x2.1mm socket and plug.