When installing a new intake manifold it is recommended to upgrade your intake bolts, some standard intake manifold wont work depending on aftermarket intake manifolds. These Aeroflow intake bolts are made from Grade 8 steel for strength. They are zinc coated for protection and long-lasting durability. Each 12-point head is designed to take a 3/8" spanner size. This compact 12-point head is ideal for use where space is minimal on most aftermarket intake manifolds compared to the factory bolts with a larger head. Each set includes special extra thick flat washers for optimum clamping pressures to ensure a sure seal.