Male DC Connector 5.5x2.5
These are connectors with male power pins and a terminal block where power is connected through the terminal block that is on board. This terminal block is a screw type terminal block where cables are connected in to it and then screwed to fix them tightly on this pin hence reducing loose connections.
This terminal block has markings on it that show positive and negative, The – or minus sign shows where the negative terminal is to be connected and the  +or plus sign shows where the positive terminal is to be connected.