Summary: So I don't know what size this drive is in MM or inches but its like in between 3.5 and 2.5.. Its a very odd size that will not fit a macbook Pro or even a Asus G75 laptop. Also the drive was DOA (dead on arrival) Maybe its just bad luck but for you guys looking to buy for a laptop please find the size to the MM of the drive.
Summary: I'm sure I would like this as my external storage, but it didn't make it through the second time I formatted the drive on my MacBook Pro, which was less than 30 days from purchase. The drive failed to spin up. I never got a chance to test the drive for speed. The other problem with it is that it won't fit in a thin case. I had to purchase a different case for it.
Summary: I originally purchased this used on Amazon and sent it back because the spindle wouldn't spin up. I then purchased this one at full price and found I had the same problem. Turns out the drive needs 5V and 12V, but most if not all small external drive cases only supply 5 Volts because of the USB specification. I purchased an adapter that works with 2.5 or 3.5 bare drives, and has an AC adapter that provides the 12V while the USB connection provides the 5V.
Summary: I was building a 2U Intel server with the Grizzly Pass server boards and needed a few SATA RAID drives. The chassis has 8 SATA 2.5 inch slots. I started with two Contesllation drives in RAID-1 configuration. While some people put the OS on two RAID 0 drives spinning at 10K RPM, I found that the 7200 RPM Contellation drives are about as good. I would rather add SSD's thatn goping with the more noisy and power hungry 10K's.