This 4-Slot KSU provides universal PCB slots and a power supply. Up to 48 ports (24 possible trunks and up to 40 extensions, maximum total of 48). System has a flip-off cover, mounts on the wall, and has a removable side panel for easy access. First slot requires a 16DSTU PCB (Part. #80021A). Cabinet accepts either "A" or "non-A" PCBs series power supplies. DS2000 is subject to "Load factors".