The Y-Cable is designed for the CS40 to provide both fast charge as well as active sync communications. Most PC’s provide only 500 mA (trickle charge when the unit is on) and the CS40 needs 1A to achieve fast charge rates. Connect the red to power and the black to the PC for fast charge and active sync. The cable will not work if either power or data are not connected. This listed part number is for the cable only as the power supply is included with every CS40.