US Patent 8435137 Golf club head

A hollow golf club head is disclosed, wherein a front member including a face portion and a hosel portion of the club head is made of a material having a specific gravity ρ1; a rear member forming a backmost point of the club head is made of a material having a specific gravity ρ2; and an intermediate member extending annularly through in a crown portion, a sole portion and a sidewall portion of the head is made of a material having a specific gravity ρ3; and the specific gravity ρ3 is more than the specific gravity ρ1 which is more than the specific gravity ρ2.