Get three, three, three functions in one cable with the Monoprice USB 2.0 Active Extension/Repeater/Hub! You can extend the length of your USB 2.0 cable an additional 16 feet with this cable. It comes with a USB A male connector on one end and a pair of USB A female connectors on the other. When extending USB cables beyond about 15 feet, you can suffer from signal strength reduction. The further you go, the worse it becomes until you get poor (or no) valid connections. This cable includes a signal amplifier, which will boost the signal strength so you can extend further without signal loss. It draws on USB power to provide the boost or can use an optional AC adapter (not included) for the power it needs. This cable is also serves as a 2-port USB hub. Each of the two USB A female connectors can connect to a discrete USB device and the cable will manage data signals in the same way as any other USB hub. The cable can be used as a passive hub or active, using the optional AC power adapter (not included) connected to the repeater unit, allowing the cable to drive power-hungry USB devices, such as portable hard drives or for phone charging. The repeater unit has two LEDs, one to indicate when an external power source is connected and the other to indicate when a valid USB data link is established with one or both of the hub ports. The optional power supply will have a power rating of 5 VDC at 1A. The connector size is 3.8 mm barrel and a 1.3 mm pin diameter. PID 2220 AC Power Adapter 5.0V/1.0A is the correct adapter to use for this cable.