I received the Mophie Power Reserve  as a door gift at the official launch of Mophie in Singapore . It is retailing for S$69 in Singapore and you can get it from the Apple Online Store (Singapore) . Last I heard, this product is going to be discontinued, so get it while you can.
Mophie Power Reserve is a 1,350mAh power bank that weighs 55g and measures 72 x 38 x 14 (L x W x H) (mm). It comes in four colors: black, white, gold and red.
It features a built-in lightning cable and has a keyring for you to attach it to your keychain. Because it is lightweight, it is mean for you to carry around and use it as a last resort to charge your iPhone and hence the word “reserve” in the product name.
It produces an output of 1A and the 1,350mAh battery should be able to charge your iPhone to more than 50% expect for the iPhone 6 Plus which will get you to about 40%.