It's a power cable adapter.
Great price. Eliminates lots of clutter when using SATA drive with older power supply. With both plugs combined it stays connected to drive better as well.
Good approach to convert older PC power supplies to power SATA HDD. Better fit using this than seperate power and data cables.
Awesome folks, huge stock and it's actually in stock (WAC), fast shipping. One of my few favorites for electronics and parts. A+ Solid.