Third Rail Mobility has unveiled its new modular Battery Case system for the iPhone 4. Unlike traditional battery cases, which feature integrated, non-removable batteries, Third Rail’s solution combines a slim case with a detachable 1250 mAh lithium ion battery pack, allowing users to remove the battery when it isn’t needed, or swap a depleted battery out for a charged cell for extended use.
In addition to charging the iPhone, the batteries can also be used to charge other devices via a micro USB adapter; the case itself offers full access to all ports, controls, and cameras, save for the Dock Connector. Third Rail Mobility’s new Battery Case system for the iPhone 4 is available now and sells for $90; the slim case is available separately for $40, while additional batteries sell for $60 each.
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