The Panamax MOD-DT4 is an add-on signal line module for Panamax protectors. Some Panamax protectors offer a screw in spot for these modules, others require making a small grounding cable to attach to a ground lug. The Panamax MOD-DT4 provides protection for up to 4 digital station (DS) set phone lines. Station Set lines that leave the building are a pathway for surges (backdoor) to enter the phone system. Multiple input & output jacks provide complete installation flexibility. Different cables/connections can be split or combined to accommodate a variety of installations.