Golf club head having improved striking face

An iron type golf club comprising:

• a club head, a grip and a shaft therebetween,
• wherein the club head is comprised of a striking face portion located at a frontal portion of the club head and a body portion comprising a hosel for receiving the shaft, a topline extending across an upper portion of the club head, a toe portion, a heel portion and a sole portion at a bottom portion of the club head;
• the striking face portion has a striking face area and comprises nine zones, including a center zone that surrounds a face center of the striking face portion, an upper center zone located between the center zone and the topline, a lower center zone located between the center zone and the sole portion, a heel center zone located between the center zone and the heel portion, a heel upper zone located between the heel center zone and the topline, a heel lower zone located between the heel center zone and the sole portion, a toe center zone located between the center zone and the toe portion, a toe upper zone located between the toe center zone and the topline, and a toe lower zone located between the toe center zone and the sole portion;
• wherein the center zone has a substantially uniform center zone thickness t1 of between 1.5 mm and 2 mm and has a center zone area A1 that is between about 15% and 30% of the striking face area;
• wherein the upper center zone has a variable thickness that increases from the center zone thickness t1 to an upper center zone maximum thickness t2 adjacent the topline and has an upper center zone area A2 that is between 5% and 15% of the striking face area, the upper center zone maximum thickness t2 is at least 25% greater than the center zone thickness t1;
• wherein the lower center zone has a variable thickness that increases from the center zone thickness t1 to a lower center zone maximum thickness t3 adjacent the sole portion;
• wherein the heel center zone has a variable thickness that increases from the center zone thickness t1 to a heel center zone maximum thickness t4 adjacent the heel portion;
• and
• wherein the toe center zone has a variable thickness that increases from the center zone thickness t1 to a toe center zone maximum thickness t7 adjacent the toe portion and has a toe center zone area A7 that is between 10% and 30% of the striking face area, the center zone thickness t1 is less than 65% of the toe center zone maximum thickness t7;
• wherein the lower center zone has a lower center zone area A3;
• wherein the heel center zone has a heel center zone area A4;
• wherein the heel upper zone has a variable thickness that increases from the center zone thickness t1 to a heel upper zone maximum thickness t5 adjacent the topline and has a heel upper zone area A5;
• wherein the heel lower zone has a variable thickness that increases from the center zone thickness t1 to a heel lower zone maximum thickness t6 adjacent the sole portion and has a heel lower zone area A6;
• wherein the toe upper zone has a variable thickness that increases from the center zone thickness t1 to a toe upper zone maximum thickness t8 adjacent the topline and has a toe upper zone area A8;
• and
• wherein the toe lower zone has a variable thickness that increases from the center zone thickness t1 to a toe lower zone maximum thickness t9 adjacent the sole portion and has a toe lower zone area A9;
• and
• wherein (A1+A7+A4)> (A2+A8+A5)+ (A3+A6+A9);
• and
• wherein t8>t7>t9>t6>t4>t5>t2>t3>t1.