If you look for an extended battery that works with basically all the iPhones and iPods that share similar connectors, the iPWR SuperPack is for you. This juice pack makes a good emergency backup battery and it works with the iPhone, iPhone 3G, iPod Touch (first and second generation), iPod video, iPod Nano (third and fourth generation), and iPod Classic.
The SuperPack comes in a nice-looking, yet cheaply made, package.
The battery has a lid that protects the USB port and connector from dust. You might lose this lid very easily, as it's completely detached and left out when the battery is attached to an iPhone or an iPod.
The battery's USB port and on/off switch are located where they can't be reached while the battery is attached to a device. This design flaw makes it impossible to charge or sync the device when the battery pack is connected to it.