This model of the iPod was originally released just 3 years after the first iPod classic was. It was more compact and provided the click wheel which later became an inspiration in the iPod classic.
1st generation
Release Date: January 6, 2004
Storage: 4GB
Battery: 8 hours of audio battery
Features: available in 5 colors and was the first product to introduce a click wheel
2nd generation
Release Date: February 22, 2005
Storage: 4GB, 6GB
Battery: 18 hours of audio battery
Features: more varied colors and an extended battery life