US Patent 9597561 Golf club head having face stress-reduction features

A golf club head comprising a body, at least one weight cartridge, and a plurality of hollow tubes is disclosed herein. The body comprises a face section, a sole section, and a return section, and also defines a hollow interior. Each of the plurality of hollow tubes extends from the return section to the sole section to reduce stresses placed on the face during impact with a golf ball, and the at least one weight cartridge is sized to fit within at least one of the plurality of hollow tubes. The sole section and return section each comprise keyed apertures providing access to the hollow tubes with which they communicate, and the at least one weight cartridge comprises a keyed structure sized to fit through the keyed apertures.