VicTec Portable Dual OTG USB Sync Adapter Spare Battery/Phone Charger Dock Holder For Samsung Galaxy S4 I9500-White Note: Compatible with Samsung Galaxy S4 ONLY Charger dock with OTG and data syncing function Can charge Spare battery and the phone at the same time It can steadily support the device and provides the users with comfortable viewing angles OTG port provides a simple way to connect phone to a USB enabled computer for data synchronization and file transfers