If you need more than four monitors on your Expandable Color Hands-Free Video Door Phone/Intercom System. or you need to extend the distance between units, this Home Run Hub enables you to expand to a total of 8 monitors . A routine installation of the video intercom uses a "daisy-chain" configuration with all units wired in series with each other. This hub is a module that enables you to run wiring in a "home run" configuration instead, which consists of separate wires running from the monitors to the hub. This can double the distance between the master and the last expansion monitor. Up to two hubs can be used to support up to 8 monitors using two HUBs.