US Patent 8066581 Putter head

Embodiments of a putter-type golf club head with an increased moment of inertia about the X axis (MOIxx) and an increased moment of inertia about the Z axis (MOIzz) are disclosed. Generally, the MOIzz is increased by designing the putter such that the center of gravity (CG) of the putter head is located at or behind the geometric center of the putter head. Additionally, the mass of the putter head is concentrated at the outer edges of the putter head. To accomplish this, the ratio of the width of the front of the putter head to the width of the rear of the putter head is no greater than 0.55:1. The MOIxx is further increased by locating the CG relatively close to the bottom of the putter head.