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.
I ordered batteries and a set of test leads. I received them within three days of when I ordered them and I got a great price. Fast service and a great price - what more could you want.