Golf club head with top line insert

1. An iron-type golf club head, comprising:

a body defining a top line comprising a recess extending along the top line no further than about halfway around a toe of the club head toward a sole of the club head, and wherein the body is formed of a first material with a first specific gravity, wherein the recess comprises a channel having a substantially rearward-facing surface facing a substantially forward-facing surface when the club is at address;

an insert positioned within the top line recess, wherein the top line insert is formed of a second material with a second specific gravity,

wherein the second specific gravity is different than the first specific gravity, and wherein the club head satisfies the relationship:

I ZZ ≧CG Z *170

where I ZZ is the rotational moment of inertia about a vertical axis and has units of g/cm 2 and CG Z is the center of gravity and has units of mm.

2. The golf club head of claim 1 , wherein the recess has a depth of more than about 0.25 mm, and further wherein the sole comprises a heel recess and a toe recess and a weight insert positioned within the sole heel recess and the sole toe recess, wherein the weight insert is formed of a third material with a third specific gravity.

3. The golf club head of claim 2 , wherein the third specific gravity is at least about 7.

4. The golf club head of claim 2 , wherein the third specific gravity is at least about 9.

5. The golf club head of claim 2 , wherein the recess extends along the top line from about 70 percent to about 95 percent of the top line length and no further.

6. The golf club head of claim 2 , wherein the recess has a depth of about 1.27 mm to about 5.08 mm.

7. The golf club head of claim 1 , wherein the second specific gravity is greater than the first specific gravity by at least about 3.

8. The golf club head of claim 7 , wherein the club head satisfies the relationship Izz>CG Z *SG*17, wherein SG is the second specific gravity.

9. The golf club head of claim 7 , wherein the second specific gravity is greater than about 9.

10. The golf club head of claim 1 , wherein the second specific gravity is less than the first specific gravity by at least about 3.

11. The golf club head of claim 10 , wherein the club head satisfies the relationship I ZZ >CG Z *SG*130, wherein SG is the second specific gravity.

12. The golf club head of claim 10 , wherein the second specific gravity is less than about 1.5.

13. The golf club head of claim 1 , wherein I ZZ is at least about 2500 g·cm 2 .

14. The golf club head of claim 1 , wherein the recess extends from the heel around the top line-toe transition.

15. The golf club head of claim 1 , wherein the recess extends along 100 percent of the top line length and no further.

16. The golf club head of claim 1 , wherein the recess extends along the top line from about 10 percent to about 50 percent of the top line length.

17. The golf club head of claim 1 , wherein the recess has a depth greater than about 0.254 mm.

18. The golf club head of claim 1 , wherein the recess has a depth from about 0.254 mm to about 6.35 mm.

19. The golf club head of claim 1 , wherein the recess has a varying depth.

20. The golf club head of claim 1 , wherein a first portion of the recess extends from the toe toward the sole and a second portion of the recess extends along the top line of the club head and the first portion of the recess has a depth about 20 percent to about 80 percent of a depth of the second portion.

21. A set of iron type golf clubs comprising:

at least one club comprising a first club head comprising:

a body defining a top line comprising a recess extending along the top line no further than about halfway around a toe of the club head toward a sole of the club head, and wherein the body is formed of a first material with a first specific gravity;

an insert positioned within the recess, wherein the insert has a second specific gravity, and wherein the second specific gravity is less than the first specific gravity; and

at least one club comprising a second club head comprising:

a body defining a top line comprising a recess extending along the top line no further than about halfway around a toe of the club head toward a sole of the club head, and wherein the body is formed of a third material with a third specific gravity;

an insert positioned within the recess, wherein the insert has a fourth specific gravity, and wherein the fourth specific gravity is greater than the third specific gravity,

wherein each recess comprises a channel having a substantially rearward-facing surface facing a substantially forward-facing surface when the club is at address.

22. The set of claim 21 , wherein at least one of the first club head and the second club head satisfy the relationship:

I ZZ ≧CGz* 170

where I ZZ is the rotational moment of inertia about a vertical axis and has units of g/cm 2 and CG Z is the center of gravity and has units of mm.

23. The set of claim 22 , wherein the I ZZ of at least one of the first club head and second club head is at least about 2500 g·cm 2 .

24. The set of claim 21 , wherein both of the first and second club heads satisfy the relationship:

I ZZ ≧CG Z *170

where I ZZ is the rotational moment of inertia about a vertical axis and has units of g/cm 2 and CG Z is the center of gravity and has units of mm.

25. The set of claim 24 , wherein the I ZZ of both the first and the second club heads is at least about 2500 g·cm 2 .

26. The set of claim 21 , wherein the second club head satisfies the relationship I ZZ ≧CG Z *SG*17, wherein SG is the fourth specific gravity.

27. The set of claim 21 , wherein the first club head satisfies the relationship I ZZ ≧CG Z *SG*130, wherein SG is the second specific gravity.

28. The set of claim 21 , wherein the recesses in the first club head and second club have a depth of more than about 1.27 mm and at least one of the recesses in the first club head and second club extend from the heel around the top line-toe transition.