Pisen 2500mAh Rechargeable External Battery Pack for iPhone/iPod - Ivory White

Pros: It's a very nice and useful Rechargeable External Battery! The material build is very good, hard (not plastic) and the recharge time from zero to completed full battery capactivity is not long (about 2 hours). The amount of energy recharged by it in the iphone is very high, reaching even to complet 100% of iphone's battery capacitivity.

Cons: The price is a little bit expansive.

Other: If you need an external battery to save your life, take it! It's really worth.

Pros: I bought this battery pack as a replacement for old one for 1000 mAh that could not handle the needs of power of my 4S. This battery pack can be taken everywhere as backup power source. When it's charged to its full capacity you can count on additional 40-50% of your iPhone 4S

Cons: Maybe the price could be lower

Other: ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Pros: Bought this battery pack to charge my phone on the go. The build for this item is sturdy, no flimsy parts or connectors to be found. It holds enough charge for approximately 1.5 full charges on an iPhone 4. A very handy item to have.

Cons: The price of this item is a bit on the high side, I feel that this battery pack could have been had for a lower price. For some reason, it takes a long time to fully charge this battery pack, about 5-6 hours even when directly connected to the mains. Charging via a USB port takes slightly longer. The battery pack makes a low whistling sound when it is low on charge, which is somewhat annoying, but this goes off when the battery pack loses all of its charge.

Other: Overpriced, but a decent buy nevertheless.