UNu has unveiled its new Ex-Era battery case for the iPhone 4 and iPhone 4S. Sporting a slide-on, detachable design, the Ex-Era allows users to remove the battery housing when not in use in order to maintain a lower profile. Other features include a swappable 1,700 mAh battery module, an included screen protector and cleaning cloth, and open access to all ports, cameras, and controls, save for the Dock Connector. uNu’s Ex-Era battery case for the iPhone 4 and iPhone 4S is available for pre-order now and sells for $80.