Iron-type golf club heads with a dual-density insert

An iron-type golf club head comprising:

• a top surface adjacent and above a ball striking surface configured for striking a ball;
• wherein the top surface defines an upper portion of the iron-type golf club head;
• a sole adjacent the ball striking surface and opposite the top surface;
• a heel side near a hosel;
• and
• a toe side opposite the hosel;
• the top surface having a width within a range of 6 mm and 8 mm, and the sole having a width within a range of 8 mm and 16 mm;
• and
• a rear surface opposite the ball striking surface comprising an upper blade portion, a blade interface portion, and a lower muscle portion;
• wherein the upper blade portion is adjacent to the top surface and extends across the rear surface from the heel side of the rear surface to the toe side of the rear surface and further extends downward from the top surface to the blade interface portion;
• wherein the blade interface portion extends across the rear surface from the heel side of the rear surface to the toe side of the rear surface and is a smooth arcuate surface extending between and in direct contact with both the upper blade portion and the lower muscle portion;
• wherein the lower muscle portion extends across the rear surface from the heel side of the rear surface to the toe side of the rear surface and the lower muscle portion extends upward from the sole to the blade interface portion, and wherein the lower muscle portion has a thickness greater than the upper blade portion, wherein the upper blade portion has a substantially constant thickness;
• a recess provided in the rear surface;
• wherein the recess comprises a recess floor that is substantially planar;
• wherein the recess floor is angled such that one portion of the recess is deeper than another portion of the recess;
• wherein the recess comprises a perimeter wall;
• wherein the perimeter wall comprises a perimeter wall height;
• wherein the perimeter wall height varies;
• and
• an insert received within the recess;
• wherein the insert is flush and contiguous with the rear surface of the iron-type golf club head;
• wherein at least a portion of the recess extends behind a location of a center of gravity of the iron-type golf club head,
• wherein the insert has a first insert having a first density and a second insert having a second density which is less than the first density,
• wherein the first insert comprises a first material, and the second insert comprises a second material;
• wherein the first material is different from the second material;
• wherein the first insert and the second insert are located adjacent and contiguous to each other, and
• wherein the first insert is located entirely within the lower muscle portion and the second insert is located within the upper blade portion, the blade interface portion, and the lower muscle portion.