The Cisco StackPower cables are thick but flexible, and they carry power as well as a data signal to provide a communications channel among the switches in the power stack. StackPower and XPS cables are keyed and have colored bands on the ends to help you understand what cable plugs into what switch or XPS. A StackPower cable has colors bands on the cable ends, green on one end and yellow on the other end. This cable can be used between Catalyst 3750-X switches and an XPS. Note that the connector with the blue band can only connect into a Catalyst 3750-X switch while the connector with the yellow band can connect to a Catalyst 3750-X or an XPS. An XPS cable has a color band on the cable ends as well, red on one end and yellow on the other end. This cable can only be used to connect Catalyst 3750-X or 3560-X switch to an XPS. Note that the connector with the red band can only connect to an XPS while the connector with the green and blue band can connect to Catalyst 3750-X or 3560-X switch. The Cisco Catalyst 3750-X Series Switches come with four power supply options and any of them can be used on any switch in a stack and in any combination.