US Patent 9662545 Golf club with coefficient of restitution feature

A golf club head includes a face; a body, the body defining an interior and an exterior; the face and the body together defining a center of gravity, the center of gravity being proximate the face; a coefficient of restitution feature defined in the body; wherein the coefficient of restitution feature defines a gap in the body. A golf club head includes a face and a golf club body; the face and the golf club body defining a center of gravity, the center of gravity defined a distance, Δz, from a ground plane as measured along a z-axis, the center of gravity defined a distance, CGy, from the center face along the y-axis.