Extra thick 0.120 inch ultra quality washers are parallel ground, heat- treated and chamfered. There washers, made of 4130 chrome moly steel can be used with both studs and bolts. The chamfered side goes up to clear the under head radius of head and main bolts, or reversed for use with studs. Torque accuracy is much improved by providing a smooth, flat bearing surface and clamping forces are more evenly spread for ultimate sealing. Perfect for aluminum heads. Black plated finish. 34 pieces per kit.