US Patent 10071291 Golf irons with sealed undercut

A golf club head includes a body, a first polymeric insert, and a second polymeric insert. The body includes a face, a sole, and a rear wall that collectively define an undercut volume. The first polymeric insert is provided within the undercut volume to define a sealed cavity within the undercut volume; and, the second polymeric insert is secured to the body and defines an open cavity extending from the rear wall toward the face.