US Patent 7097572 Golf club head

A hollow metal club head comprises a face portion whose front surface defines the club face, and a turnback wall extending backward from the circumferential edge of the face portion, wherein a head volume is in a range of not less than 440 cc, a height of the club face is in a range of from 55 to 85 mm, and a surface area of the club face is in a range of from 4000 to 6500 sq. mm. In a front end zone of the turnback wall and a peripheral zone of the face portion which are adjacent to each other through a junction between the turnback wall and the face portion, the ratio Rf/Rh of a zone rigidity Rf=(Ef×tf3) of the peripheral zone to a zone rigidity Rh=(Eh×th3) of the front end zone is in a range of from 4.0 to 12.0.