**A nitrided piston ring is a type of piston ring that has undergone a nitriding process, which is a heat treatment that diffuses nitrogen into the surface of the metal. This process creates a hard, wear-resistant surface while maintaining the toughness and flexibility of the core material. The primary benefits of nitrided piston rings include enhanced durability, reduced wear, improved resistance to high temperatures, and better sealing capabilities, making them suitable for high-performance and heavy-duty engine applications.