Excellent timing... for WD...
Now is the time to try and sell HDDs in this form factor, for such high-end use, before flash-based storage takes over the segment (all it takes is adding some storage volume/density to it).
It is dumping, fire-sale time! All the stuck kit must go NOW, before it gets rotten (or rust, in this case)!
Mine is the one with 2.5" wide pockets.