A golf club head having face, crown, sole and side portions, and comprising a metal head base body (M) having at least one opening and a cover (FR) arranged in the opening and made of a material having a specific gravity smaller than the base body, wherein when the head is sectioned into head toe side...http://www.google.es/patents/US7303487?utm_source=gb-gplus-sharePatente US7303487 - Golf club head
