Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: is it 7mm or 9.5mm?
Document: Does what I need at a reasonable price (at least when I bought it). Just to clarify though, when they say 500GB, they mean 500*10^9 or 500,000,000,000 bytes rather than the larger and more standard 500*2^30 or 536,870,912,000 bytes. The difference: approximately 34.3GB or 6.9% of the capacity you were promised.
This will drain your otherwise 7-9 hour worth of battery to 3-4 hours. I went ahead and changed mine to the 5400 RMP drive that came with my Macbook Pro.There's nothing wrong with the drive - just that its not meant for the Macbook Pro 13" mid 2010 Unibody. Before you buy this, confirm with Apple that the machine where you are going to use this actually supports this FULLY!
I want to like this but I am having trouble. This drive is not as fast in performance as Western Digital laptop 7200 RPM drives I have had in the past. It is however 7mm in thickness and that is what new laptops seem to require. It does not seem any faster in performance than the 5400 RPM drive that it replaced. The Windows score for hard drive stayed the same too.
I had to buy this drive as a replacement for the same exact model HGST drive that went bad in my Lenovo T420s ultrabook. The drive model performs great, and it was the only drive that would fit the ultrabook due to its small size (that I could find with this size and speed);  I think its 7mm, which is the height of the drive bay for the ultrabook.
I ordered the Hitachi Travelstar 7k500 with 7200 rpm and 16mb cache and instead i got a HGST Travelstar Z7k500 which is 7mm thin, 7200 rpm with 32mb cache for the same price of the 7k500. This hard drive is way better because it's only a single platter and it's more reliable. It's fast and real quiet for a 7200 rpm hard drive. Best purchased i've made this year.
works great macbook pro 2009 awesome. i love it. so worth the cost. apple store will cost 300 extra for this
used this drive to replace the 160GB drive on a 2008 aluminum MacBook. The hardware portion of the upgrade was very easy and straightforward. I did have to reinstall OSX from scratch. Startup time of the laptop is significantly shorter than before, but it can be partially due to the fresh OSX install. It has been up and running for 2 weeks, so it is too early to comment on reliability. The thing that annoys me is that this drive is significantly noisier than the original Toshiba.
used it to upgrade my laptop form 320 to 500. very good overall. have used it for around 2 months.. its oem brand, what else to say
used for 1 month. so far so good. easy to install and works great. good product as per price. replaced the 750 gb 5400rpm hdd with this one. windows experience index still the same probably due to 16 MB Cache as the old one.
to do the job. I copied the file to a location in the root folder of the old hard drive before replacing it. After replacing it, I installed the OS from my original disk and drivers (from the HP website) and did all the updates for the OS. Then I installed all the other programs like Office that I had disks for followed by any free programs that had been acquired from the internet. (I had made a list of all installed programs that I wished to keep).
Answer: It's a 7mm and works as good as a 9.5mm. Have it in my 2013 macbook pro.