US Patent 7854666 Structural response modifying features for a golf club head

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.