US Patent 10155143 Golf club head

A cavity back iron type club head includes a striking plate having a substantially planar striking surface and a rear surface defining a thickness therebetween. The rear surface defines a striking plate rear cavity region. A perimeter support is coupled to a peripheral portion of the striking plate. The surface area of the striking surface is related to the club head loft angle by the equation SSA≥14.4(L)+2875, where SSA is the surface area of the striking surface in units of square-millimeters and L is the club head loft angle in units of degrees.