Thinnest protective case with additional battery, case can also be used without the additional battery  Future-proof: Smart battery is compatible with all currently available and future protective cases from Third Rail  Universal: other phones or electrical devices can be charged with the help of the included micro USB cable 2x charging: both iPhone and Smart auxiliary battery will be charged with the same power portProtection and functionality resistant hard shell case with soft surface, provides access to all the features of the iPhone