1) USB 2.0 standard. 2) OTG Micro USB Hub . Please make sure your phone Support OTG function . (Some OTG phone may lost OTG function after rooting.) 3) 1 micro usb to 2 USB interface and 1 power supply interface. 4) The power supply interface supply the power to the hub when using 2 usb ports .(The power supply interface is not for charging phone .) 5) When connect with USB storage device it should be FAT or FAT32 format . This is limited by OTG function not our usb hub.