- Analog Station Set and Central Office Line Protector- Protects up to 8-wires (4-pairs) using 110 punchdown block on the input and 110 punchdown block or 4 RJ11 or 2 RJ45 on output.- Auto-Resetting Technology: PTC resistors open when a surge occurs, protecting your equipment, but unlike other fuses, the PTCs close again once the surge passes.- Expandable modular system- Applications: Analog and Central Office lines for PBX or KSU - Agency Approval: UL 497A (Secondary)- Grounding Requirements: Uses Electrical AC Ground- Recommended Grounding Impedance: