Square D Surge Arrestor For Voltage Surge Protection On Secondary Electrical Wiring Protects From Surges Up To 20,000 Volts Mounts On All Service Entrance Equipment For Two Or Three Wire Grounded Service Can Be Installed Indoors Or Outdoors Unit Includes Mounting Hard- Ware And 18 Leads Ul Listed And Csa Certified Boxed All items sold new in original packaging