16px 32px 128px 256px (OS X 10.5+) 512px (OS X 10.5+) 1024px (OS X 10.7+) Examples of how the icon resources are used: 16px - list views, spotlight searches 32px - Finder 128px - Dock, Finder previews 256px - Finder preview 512px - CoverFlow See chapter 7 of the Icon Handbook for more information