Battery: Built-in rechargeable lithium ion battery
Power: Charging via FireWire, USB 2 (high power) or power adapter
Playtime: Up to 12 hours
Operating Temperature: 32 to 113 deg. F (0 to 45 deg. C)
Storage Temperature: -4 to 158 deg. F (-20 to 70 deg. C)
Relative Humidity: 5% to 95% noncondensing
Altitude: 10,000 feet (3000 m)
History: On July 19th, 2004, Apple released the fourth iPod generation. The new model was slightly slimmer, shipped in either 20 or 40 GB configuration, had up to 12 hours battery life and featured the Apple Click Wheel, which debuted on the iPod mini. The price for the entry model dropped to $299 U.S. and the 40 GB was $399 U.S.
History Source: The Apple Museum
History Source Address: http://www.theapplemuseum.com/