US Patent 8241143 Hollow golf club head having sole stress reducing feature

A hollow golf club incorporating a stress reducing feature including a sole located stress reducing feature located on the sole of the club head. The location and size of the sole stress reducing feature, and their relationship to one another and other club head engineering variables, play a significant role in reducing the peak stress seen on the golf club's face during an impact with a golf ball, as well as selectively increasing deflection of the face.