A bracket, some antenna cables, a few screws, and finally we get to the crème de la crème, the fan with asymmetric blade spacing.

We jumped at calling the fan inside the Mid-2012 MacBook Air 13" "asymmetrical," but when compared to the fan inside this MacBook Pro, the Air's fan is definitely more periodic.

Theoretically, the asymmetry spreads the noise produced over multiple frequencies, making it less noticeable.

This fan has been mentioned in almost all press on the MacBook Pro with Retina display. We are surprised at how much attention a minor blade spacing change is getting. It is nevertheless a testament to how much attention Apple puts on minor details overlooked by the rest of the industry, all for the comfort of the end user.