iPod nano 4th generation

At the Apple Let's Rock Event on September 9, 2008, the iPod nano Fourth Generation was officially announced.It returned to the narrow form factor of the 1st and 2nd Generation model, while retaining and rotating the 51-millimetre (2.0 in) screen from the 3rd gen model. It was also thinner than the 1G, 2G and 3G, measuring 90.7 millimetres (3.57 in) tall by 38.7 millimetres (1.52 in) wide by 6.2 millimetres (0.24 in) thick, and weighing 36.8 grams (1.30 oz). It had a curved aluminum shell and glass screen (the glass screen being held in place with nothing but the shell). Apple claimed the battery would last 24 hours of music playback, and only 4 hours of video playback, compared to the 5 hours of the previous generation.