The 4-pin Molex connector is pretty standard for disk drives and things like that but it’s also a great general purpose power connector. If you’re using a computer power supply to juice-up your project, this is a nice clean way to hook it up.
These pigtail connectors break out to 4 standard-color 1ft. leads. When connected to a standard supply the yellow wire will be the 12V line, the red wire will be 5V and the black wires will be the ground connection.