Complex sentence: The DSi XL stylus is 96mm long, just 4mm longer than the stylus on the DSi, but the XL also includes a 129.3mm-long pen-shaped stylus, which does not fit inside the console.
Split into simpler sentences: The DSi XL stylus is 96mm long, just 4mm longer than the stylus on the DSi. The XL also includes a 129.3mm-long pen-shaped stylus, which does not fit inside the console.