This product was quite expensive when I ended up paying £12 for this, plus £5 postage. However for the price, it delivers completely!
As the manufacturer and other reviewers state, the dimensions of the dock are exactly those of your average 3.5 inch hard drive. My case has a strange caddy system which infuriates me no end but at least holds the drives in place, and this one offered no extra challenge. If your case can hold 3.5 inch drives, it can hold this.
You connect the 2.5 SSD or hard drive to a little converter INSIDE the dock, and there are ports attached to the OUTSIDE of the dock. I prefer this to having a direct connection between SATA/power cables and the drive as I'm worried about damaging my SSD. Not sure how realistic the risk is, I think I'm just paranoid!
Pads are provided to help fit the 2.5 SSD/HDD snugly inside the case. No problems arose from that bit, though the locking mechanism put me off a little - before I realised that the backing of the enclosure held the tab which in turn held the drive in place. I think this could've been done better (quick lock/quick remove metal pins to hold it in place perhaps), but admittedly the holes aren't always in the same places on the drive, whereas this solution works for most drives.
There are cooling holes, so hot air will be able to vent, and it doesn't look like this case, being made of hardened plastic, will melt in action any time soon.
Overall, it's flexible and I imagine will work for most 2.5 inch SSDs and HDDs (I use the Crucial CT064M4SSD2 64GB M4 SSD
with success) and on inspection it should fit virtually any 3.5 drive bay, and is hot-swappable with other cases. Four stars for this one, I think £12 was a little too much, but otherwise a fantastic product!