US Patent 6964620 Golf club iron

A golf club iron having a thin front face supported by a biasly bent U-shaped insert that is inserted into a rear cavity and sole recess of the iron to not only support the front face and to create a “spring like” effect, but to create a void between the insert and the front face and sole portion of the club head. The coefficient of restitution of the club head is greater than 0.8. The insert has a lower specific gravity and a higher Young's Modulus than the front face.