In most cases, we can replace the built-in battery in an iPhone 4 battery case, but if you want, MiPow’s Clone Power iPhone 4 case with replaceable back up battery may be more suitable for you.
MiPow Clone Power iPhone 4 case measures 127 x 61.6 x 16.5mm and weights 125g. Unlike common iPhone 4 battery case with built-in rechargeable battery, Clone Power Case features a replaceable back up battery with 1500mAh capacity to feed your iPhone 4 battery out of juice, and using the additional battery, the battery case will extend the battery life of your iPhone for a longer time. And it also comes with On/Off switch and LED indicator for charging status. Apart from that, the transparent plastic hardshell case can also protect the iPhone from scratches and bumps, while the cutouts let you access to all iPhone 4 buttons and functions.
MiPow Clone Power iPhone 4 case with replaceable back up battery is priced at $69 USD. If you’re interested, jump to MiPow official site for more details. Additionally, if you need more options, you may like to check PhoneSuit Elite battery case, Third Rail iPhone 4 case, and more via “iPhone 4 case” tag.