MSD OVERSIZE DISTRIBUTOR GEAR, BRONZE -- 0.006 in; Includes roll pin; Machined from quality AMPCO 45 aluminum bronze containing 5 percent nickel that makes a special combination which creates high-strength gear teeth that are less prone to wear even with high volume pumps; For MSD aftermarket distributors with 0.5 in. diameter shaft; Requires drilling; Not intended for extended street use.