Back up battery packs?

[dill84]

I am looking for recommendations for a back up battery pack like the Mophie for charging USB devices in the field. I need to be able to use an Iphone 5 without plugging it in every six hours.

Thanks

 

[BoilerUP]

Amazon.com: New Trent iCarrier 12000mAh Portable Dual USB Port External Battery Charger/Power Pack for Smartphones, Tablets and more (Now w/Micro-USB charge port): Cell Phones & Accessories

 

[knockemdown]

I have this New Trent 12,000 mAh pack,
New Trent PowerPak Xtreme NT120R, iPhone External Portable Rugged battery pack, Android Portable Rugged External Battery, Tablet iPad Battery | NewTrent.com
Being water/dirt/shock resistant, its better suited for outdoor use (camping/hiking/hunting, etc)...