The used TP-DCDC-2USB-48 Passive Power Over Ethernet Power Source offered by Tycon Power Systems is a unique 48VDC Passive PoE injector powered by two USB ports.
They work by supplying power to the remote device on the 4 unused Ethernet pins 4,5(+) and 7,8(-). The Ethernet spec supports distances up to 100m (328 feet).