3.70V,800mAh,Li-ion,White,Hi-quality Replacement MP3 Player Battery for CREATIVE NOMAD MuVo2, Jukebox Zen Xtra, Jukebox Zen NX,Compatible Part Numbers: 331A4Z20DE2D, 73PD000000005, BA20203R79902, DAP-MVAB1(Remark:NOT Compatible with NOMAD Jukebox 20GB, NOMAD Jukebox 10GB, NOMAD Jukebox, or NOMAD Jukebox C)
I ordered two of these batteries for my old Zen Xtra.  As others have said, this battery is a fraction smaller than the original one and it will require a simple shim of some sort.  One could use a toothpick, a piece of plastic, or some strips of electrical tape attached to the end of the battery.  It's not really a big deal and otherwise these batteries work fine.  Considering that these Zen players are dinasaurs age-wise we're lucky to be able to find batteries at such a low price.  Actually my biggest co