Golf club head with variable center of gravity

A golf club head comprising:

• a substantially vertical hosel adapted for attachment to a shaft;
• said head having horizontal top and sole portions extending between a toe portion and heel portion with an inclined front face in a single plane and curved back face;
• said back face having a contour of variable radii of curvature from a larger radius at the top horizontal portion of the head to a smaller radius of curvature at the horizontal sole portion of the head;
• said back face comprising recesses inset in said back face of larger radius of curvature including one upper long recess and two lower separate shorter recesses with two rims in the same plane and coextensive with and just below the upper recess;
• said lower recesses being capable of retaining a plurality of additive mass means and being completely separated by a vertical partition, the bottom thereof being flat and substantially parallel to the contour of the back face;
• additive mass means for insertion in said two lower recesses;
• a fourth recess comprising said lower recesses and having in the contour of very large radius of curvature a further rim separated from the plane of the rims of said two lower recesses, said rim of said fourth recess being outside the rims of the two lower recesses in countersuck fashion;
• and
• a cover element for insertion in said fourth recess to cover said additive mass while being flush with said contour of said back face with said radius of curvature.