Its precedessor used one more platter

This 2-platter drive replaces the 3-platter 500GB SpinPoint M6 released in 2008:

http://www.engadget.com/2008/01/06/samsung-intros-spinpoint-m6-500gb-standard-height-laptop-drive/

http://www.engadget.com/2008/06/10/samsung-stops-teasing-brings-spinpoint-m6-500gb-stateside/

It was Hitachi that released a 2.5-inch 500GB hard drive that, at 12.5mm, was too tall to fit a standard laptop, no doubt making life miserable for its public relations folks:

http://www.engadget.com/2008/01/03/hitachis-5k500-e5k500-hit-the-mythical-500gb-mark-for-laptops/