6 point thin wall mirror polished chrome vanadium socket with dual grease rings. Oversized callout forged into socket wall for quick and easy size identification, and will not rub off, wear out or rust with use. Rubber insert holds spark plug securely Chamfered opening for easier mating to fasteners. Z-Drive hex design contacts flat walls of fasteners for stronger grip. Meets or exceeds ANSI standards. Lifetime warranty.