Abstract: A muscle-back iron golf club head includes a blade-like upper mass, a muscle-like lower mass, a planar front surface, a top surface, a sole surface, a heel surface, a toe surface, and a rear surface having a first contour. A recess is in the rear surface, the recess having a first portion in the blade-like upper mass and a second portion in the muscle-like lower mass. An insert may be provided in the recess, and such insert may substantially fill the recess and may include a back surface having a second contour which is different from the first contour of the club head rear surface.

Abstract: A golf club head having a crown, a sole having a length, ls, a strike face, a structural response modifying element having a constraining portion and a cantilever portion, the constraining portion extending from the sole to the crown and having a length lsc that is between about 10% to about 40% of length ls, wherein the cantilever portion extends from the constraining member toward the strike face. In another embodiment the constraining portion extends from the crown to a skirt portion of the club head, but is not connected to the strike face.

Abstract: A muscle-back iron golf club head includes a blade-like upper mass, a muscle-like lower mass, a planar front surface, a top surface, a sole surface, a heel surface, a toe surface, and a rear surface having a first contour. A recess is in the rear surface, the recess having a first portion in the blade-like upper mass and a second portion in the muscle-like lower mass. An insert may be provided in the recess, and such insert may substantially fill the recess and may include a back surface having a second contour which is different from the first contour of the club head rear surface.

Abstract: A hollow wood-type golf club head having an increased weight budget and improved mass characteristics at minimum structural mass is disclosed. The club head has a striking face portion, a sole portion, a skirt portion, and a crown portion having a total surface area. A hosel portion joins the club head for connecting a shaft to the club head. The crown portion has a major crown portion and a minor crown portion, the major portion having greater surface area than the minor portion, and the major portion being displaced vertically lower relative to the minor crown portion. The major crown portion may have a generally concave curvature and the minor crown portion may have a generally convex curvature such that the major crown portion is in effect inverted with respect to the minor crown portion. The major crown portion may be upwardly inclined from the heel to the toe of the head. The head may exhibit a parabolic top view silhouette.