What is a reliable battery pack for an iPhone 5?

I need to purchase a battery pack for my iPhone 5, something that would extend my battery life for a few hours longer/ charge my iPhone while on the go. I need it to be something reasonable in price too. Is there a specific battery pack that you would recommend?

Product review would be awesome!

I use a Mophie juice pack plus for my iPhone 4s - and if I was using a iPhone 5, would get the same.

http://www.amazon.com/...B00AX49VBW
Mophie makes similar add-ons (like the "Helium") that are less money and less additional battery time. Product reviews are at the Amazon link. I got mine at the Verizon store.