The USB sync cable does fit my Zire 31, and luckily that's the primary reason I bought this kit. The charging cable definitely doesn't fit the little hole on the Zire 31, though. So at this point (based on the earlier reviews) I'm wondering which, if any, of the Zire models this kit was intended for -- just the basic Zire 21 (or whatever the model number for the B&W version is)?