This is a Flying Busboard Cable, a ribbon cable designed to connect power from the Tip Top uZeus power supply to the individual modules, but can also be used to add a five more connectors to any eurorack power supply, provided you can spare the power!

This can come in handy in systems that use multiple small 2-4hp modules that use up connectors quickly or to expand a uZeus, especially after upgrading the uZeus power supply to the 3000mA Mantis / uZeus boost supply from Tip Top Audio.