Patent ID: 7686707

Claim:
A hollow golf club head comprising: a first recess portion formed in a portion of said head; a second recess portion formed in another portion of said head; a first viscoelastic body made of a first viscoelastic material, said first viscoelastic body fixed in said first recess portion; a second viscoelastic body made of a second viscoelastic material, said second viscoelastic body fixed in said second recess portion; a first cover member provided with said first recess portion and covering the whole first viscoelastic body; and a second cover member provided with said second recess portion and covering the whole second viscoelastic body, wherein said first viscoelastic material has a peak value temperature of the loss coefficient which is less than −30° C. and said second viscoelastic material has a peak value temperature of the loss coefficient which is not less than −30° C., wherein said first viscoelastic material comprises one of a butyl bromide composition, an acrylonitrile-butadiene rubber, silicone rubber and styrene-based rubber, and said second viscoelastic material comprises one of a butyl bromide composition, an acrylonitrile-butadiene rubber, silicone rubber and styrene-based rubber, and wherein said first recess portion is formed in a sole portion of said head, and said second recess portion is formed in a side portion of said head.