The 7mm, 9mm, or 9.5mm specifications would be the thickness of the drive. I can understand your worries because if you are confined to only using 7mm then a 9mm would not work. However the link I provided above shows a HDD upgrade that is 9.5mm in size. If you do have clearance for 9.5mm, you will not have any issues with a drive that is 7mm or 9mm as they are thinner drives.