A lightning ro (USA) or lightning conductor (UK) is a single component in a lightning protection system. In addition to rods placed at regular intervals on the highest portions of a structure, a lightning protection system typically includes a rooftop network of conductors, multiple conductive paths from the roof to the ground, bonding connections to metallic objects within the structure and a grounding network. The actual rooftop lightning rod is a metal strip or rod, usually of copper or similar conductive material. Lightning protection systems are installed on structures, trees, monuments, bridges and even water vessels to protect from lightning damage. Individual lightning rods are sometimes called finials, air terminals or strike termination devices. The United States Patent Office labels "Lightning protectors" in Class 174 (Electricity: conductors and insulators), Subclass 2 (Lightning protectors) and Subclass 3 (Rods).