Great site, many possibilities for a battery replacement, as the amount of products supplied looks impressive. Site's policy of prompt delivery (around 5 business days) inside Europe is most convincing! I will certainly revisit you when the next battery replacement is needed.
About the product:
Battery looks good for the Nomad ZEN, although I would expect a little more than 8.5 hours of playback. Nevertheless, battery lifetime will be the most decisive factor for final verdict, but this will take time to see.