Lightning rod

A lightning rod (or lightning protector) (USA) or "lightning conductor" (UK), is a metal strip or rod, usually of copper or similar conductive material, a lightning safety measure designed to protect tall or isolated structures (such as the roof of a building or the mast of a vessel) from lightning damage. Its formal name is lightning finial or air terminal. Sometimes, the system is referred to as a lightning discharger; however, this term is more often used to refer to lightning protection systems in general or specific components within them. The United States Patent Office labels "Lightning protectors" in Class 174 (Electricity: conductors and insulators), Subclass 2 (Lightning protectors) and Subclass 3 (Rods).