This is basically a pass-through which takes one SATA power connector and gives you two more. The pass-through part is plastic which is slightly thicker on the male end than a normal SATA power connector. As a result, on the particular drive I used it on plugging in the SATA data cable became a bit of a squeeze and prevented it from locking in completely. Seems to work fine.
Also, there was an alignment tab on the female end of the splitter which on mine arrived snapped off. Doesn't really affect performance or usage.
If you need to add a SATA power connector to your PC to accommodate an additional drive as I did, this is it. It cost me an additional $4.99 for cheapest shipping, so you're really looking at a $10.79 cable with a 3-4 day delivery. It either works or it doesn't, not much else to expect or say about a cable. Mine works.
I bought these to replace the connectors that came with my power supply. Those connectors kept coming loose from the hard drives. These adapters connect very positively with the hard drives and all is well.
Works as promised, but make sure it fits in your case
Works great, but make sure your case will accommodate the pass through adapter. My case (a Lian-Li/Lancool PC-K7) did not have enough space behind the drive cage to accommodate the pass through connector. I can use it as a traditional power splitter, but the pass through won't work.
PROS: Provides power to multiple SATA devices
CONS: Not all cases will accommodate the pass through adapter