Increase the power running to a portable hard drive from your PC or Mac! When a standard USB (Universal Serial Bus) cable cannot transfer enough power to operate an external device, such as a portable hard drive, you need a USB (Universal Serial Bus) 2.0 Y-cable. Simply plug this cable's USB (Universal Serial Bus) B end into the device, & then plug the two USB (Universal Serial Bus) A ends into open USB (Universal Serial Bus) ports on one desktop PC or Mac. This cable then pulls power from both USB (Universal Serial Bus) ports, & thus increases the output to the external drive. The molded hood on the auxiliary USB (Universal Serial Bus) A connector enables the user to quickly distinguish between main & auxiliary power. Foil & braid shielding reduces EMI/RFI interference, & twisted pair construction reduces crosstalk for high speed, error-free data transfer. This cable is compatible with USB (Universal Serial Bus) 1.0, 1.1, & 2.0 specifications.