Mobility Cable: MicroUSB-to-MicroUSB OTG
MicroUSB-to-MicroUSB OTG cable lets you connect two devices with MicroUSB ports for charging and data transfer: two smartphones or tablets, tablet and phone, or a portable external hard drive/SSD and a phone or tablet.
One end of the cable is marked as "Host" which should be plugged into the "master" device which provides power to the other device.