MSD BRONZE DISTRIBUTOR GEAR -- Fits Chevrolet .500 in. I.D; A durable, accurate, and strong distributor gear from a variety of metallurgical compositions, heat treating, and coatings; Machined from quality Ampco 45 aluminum bronze containing 5 percent nickel; Features high strength gear teeth that are less prone to wear even with high volume oil pumps; With 1-year MSD limited warranty.