Ranger BC and Doubles

[dblthunder]

Hello, I need some help concerning the use of doubles and a ranger bc. My friend had his backplate or whatever he used and his tanks bands stolen out of his truck. I would like to get these for him as a surprize but I know nothing about ranger bc's. Even when I go to their website I cannot figure out how one converts a ranger bc to accept doubles. I would really appreciate if someone could let me know what parts or if any backplate will work. I imgine tank bands are tanks bands, but how it is configured to accept doubles has me stumped...
Thanks

 

[MattJ]

http://www.zeagle.com/clientuploads/Manuals/BC_owners_Manual.pdf

The part you're interested in looks to start on about page 12.

 

[dblthunder]

Thanks, appreciate the help....