Atom 3.1 battery and strap?

I may have over looked both of these items but I really haven't been able to find the answers. I am wondering about the battery and if the user can change it out? I am also seeing on your site that if I am on the Geo 2.0 page and see a velcro strap for Atom/Geo but then not on the page for the Atom 3.1, can it be used on both? I am also wondering if you recommend one over the other for freediving (Geo or Atom)? I mostly freedive but I don't think it's a bad idea to have both scuba and Freedive on one computer! I have seen that most computers of this type don't start "reading" in freedive until 1.5m but you have to give something I guess.

Thanks,
Derek

Don't know if you got your answer yet, but I have the velcro strap for my Atom 3.0 and it works just fine. The battery on the Atom 3.0 is also user replaceable and it comes with the tool to open the watch. The only difference between the 3.1 and 3.0 is that the 3.1 doesn't have the buddy pressure check (they had to remove it due to patent issues).

Thanks for that Cero21!