These Expansion Plug is made from brass.  It designed to fit:

1947-1950 Chevrolet Fleetline

1950 Chevrolet Bel Air

1947-1948 Chevrolet Fleetmaster

1949-1950 Chevrolet Styleline Deluxe

1949-1950 Chevrolet Styleline Special

1947-1948 Chevrolet Stylemaster Series

The Dorman 565-028 Engine Expansion Plug is a high-quality replacement part designed to fit one engine rocker arm shaft end. Manufactured by Dorman, this plug comes with a 1-month manufacturer warranty for added peace of mind. With the manufacturer part number 565-028, this product is a reliable choice for maintaining the proper function of your vehicle's valvetrain system.