Not your ordinary hardware store variety! Moroso Head Bolt Washers are designed for the racer; machined from tough 4130 chrome moly steel, heat-treated to proper hardness, and parallel-ground. Stress loads are more evenly distributed and torque readings more accurate. Can also be used on main bearing caps, rocker arm stands, and other engine components. Use them over and over again. These washers are a must when using aluminum heads. Chamfered side of the washer should be toward the head of the bolt.