The G4 iBooks replaced the G3 "Snow" models in October 2003, being the last computer in Apple's lineup to receive a G4 update. They retained a very similar design to the late-model G3 "Snow" models, but they did feature an updated keyboard. Speeds topped out at 1.33GHz on the 12" models, and 1.42GHz on the 14" models.
Due to the number of revisions these laptops had, building out spec lists for each would take hours. That's something I may still do in the future, but for now, I'm just going to link to everymac.com's section for these laptops.
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