Help guys, Urgent. 800gs Battery info.

Hi all. My father is stuck out on a ride because of a faulty battery. I need the correct battery code to give him so he can ask for a replacement one. Im not entirely sure what information I need, but basically he can get hold of a battery shop and needs to comunicate what battery he needs to replace his defunct one. You can tell by the roudabout way I am saying this that I am the weak link here  :imaposer: :imaposer: :imaposer:                                                                                                                                  . It's a 2008 800gs. If you can help asap that would be greatly appreciated by all. Cheers.