It's the 4-pin (+5VDC, +12VDC, GND GND) disk systems (HDD, CD-ROM) power plug for socket contacts. I had a project I was using just the sockets for, and decided to model this as an exercise. Features include treads and wings for easy removal, and a pin 1 marker. It looks swell! Sometimes called a "Molex plug," it is made by many different manufacturers.Print it solid, with small layers for good accuracy. It can print without support, even though there is a small overhang. If you print this in Nylon (the native material for this type of plug), let me know. :-)