The physically rotating wheel was surrounded by another wheel of buttons. the Click Wheel didn't appear until the mini. 1st gen: mechanical wheel with a surrounding wheel of buttons. 2nd gen: touch wheel surrounded by buttons. 3rd gen: all touch with a row of buttons under the screen.<p><a href="http://support.apple.com/kb/HT1353" rel="nofollow">http://support.apple.com/kb/HT1353</a> identifies the iPod (Click Wheel) as their 2004 model.