Patent 7186187 was granted and assigned to Acushnet (company) on March, 2007 by the United States Patent and Trademark Office.
A set of iron-type golf clubs includes long irons with cavity back configurations and short irons with muscle back configurations. The rear face configurations slowly transition from pure cavity back through cavity-muscle backs to pure muscle backs for increased performance continuum for the set. Additional design parameters for the set may also be systematically varied through the set, such as face area, loft angle, offset and location of the center of gravity.