The Apple iPod nano (Fourth Generation), seemingly in response to the lukewarm reception of the "fat" iPod nano (3rd Gen), returned to a design more reminiscent of the "skinny" iPod nano (2nd Gen). It showcased a new, slightly thinner (by 0.02 inches) wraparound "curved aluminum and glass" case available in nine colors: silver, black, purple, blue, green, yellow, orange, pink, and a (PRODUCT) RED Special Edition. It also featured a portrait-oriented 2-inch (diagonal) color LCD with a blue-white LED backlight (320x240, 204 ppi).
It was offered with either 8 GB or 16 GB* of flash memory, holding 2000 or 4000 songs, 7000 or 14,000 photos, and 8 or 16 hours of video, respectively. Unlike previous models, all colors were available for both capacities.
Key enhancements over the 3rd Gen model included a built-in accelerometer that automatically switched to "Cover Flow" when the device was rotated to landscape (games and videos were landscape-only), a new "Genius" feature for creating dynamic playlists of complementary songs, and a "shake to shuffle" function. Music battery life remained at 24 hours, but video playback was reduced to 4 hours from the previous 5.
The interface was enhanced while retaining the "MacOS X Leopard" inspired elements, and it added new accessibility options like larger text and spoken menus.