2steel, carburized and hardened case depth .020-.030 rockwell a 76-81, 0.875 in.Lg o/a, 0.187 in. Head lg, 0.438 in. Head od, 0.688 in. Stem lg, 0.156 in. Stem dia, stem end rounded on 0.078 in. Radius, 0.062 in. Depth by 0.219 in. Radius concave head