Putter-type golf club head

A putter head configured to be attached to a shaft having a shaft axis oriented at a lie angle and a lean angle, comprising:

• a top portion, a sole portion, a striking face having a leading edge, and a rear portion having a rearwardmost point;
• a putter head mass of 250-370 grams, a putter length of at least 72 mm, a putter width;
• a through opening extending vertically through the putter head and having a forwardmost opening point, a rearwardmost opening point, a max opening width, and a max opening length greater than the max opening width;
• wherein:
• the striking face has a striking face width and a geometric center defining an origin for a club head origin X-axis, a club head origin Y-axis, and a club head origin Z-axis;
• the putter head has a center of gravity CG located at a head origin X-axis CGx coordinate, a head origin Y-axis CGy coordinate, a Zup value above a ground plane, and defining a center-of-gravity coordinate system having a CG X-axis, a CG Y-axis, and a CG Z-axis;
• a face center horizontal plane contains the club head origin X-axis and the club head origin Y-axis, a face center vertical plane contains the club head origin Y-axis and the club head origin Z-axis, and the face center vertical plane separates a heel half of the putter head from a toe half of the putter head;
• a projection of the center of gravity CG vertically onto the face center horizontal plane produces a projection intersection point located within a CG variation angle of less than 45 degrees, where an apex of the CG variation angle is located in the face center horizontal plane at a point that the shaft axis intersects the face center horizontal plane, and CG variation angle opens symmetrically from the apex about a vertical apex plane containing the apex and parallel to the club head origin X-axis;
• the putter head has an inertia tensor including a Ixx moment of inertia about the CG X-axis, a Iyy moment of inertia about the CG Y-axis, a Izz moment of inertia about the CG Z-axis, a Ixy product of inertia, a Ixz product of inertia, a Iyx product of inertia, a Iyz product of inertia, a Izx product of inertia, and a Izy product of inertia;
• an absolute value of the Iyz product of inertia is 2.75-5.5% of the Ixx moment of inertia;
• an absolute value of the Ixz product of inertia is less than 0.1% of the Iyy moment of inertia;
• a forward-upright product is a product of the CGy coordinate and the lean angle, and the forward-upright product is 17.5-53 mm degrees;
• a low-forward product is a product of the CGy coordinate and the Zup value, and the low-forward product is 225-400 mm2;
• and
• a low-forward-lean product is a product of the low-forward product and an absolute value of the lean angle, and the low-forward-lean product is 225-550 mm2 degrees.

A putter head configured to be attached to a shaft having a shaft axis oriented at a lie angle and a lean angle, comprising:

• a top portion, a sole portion, a striking face having a leading edge, and a rear portion having a rearwardmost point;
• a putter head mass of 250-370 grams, a putter length of at least 72 mm, a putter width including a maximum putter width, a minimum putter width at least 7% less than the maximum putter width, and a post-minimum putter width of 102-135% the minimum putter width;
• wherein:
• the striking face has a striking face width and a geometric center defining an origin for a club head origin X-axis, a club head origin Y-axis, and a club head origin Z-axis;
• the putter head has a center of gravity CG located at a head origin X-axis CGx coordinate, a head origin Y-axis CGy coordinate, a Zup value above a ground plane, and defining a center-of-gravity coordinate system having a CG X-axis, a CG Y-axis, and a CG Z-axis;
• a face center horizontal plane contains the club head origin X-axis and the club head origin Y-axis, a face center vertical plane contains the club head origin Y-axis and the club head origin Z-axis, and the face center vertical plane separates a heel half of the putter head from a toe half of the putter head;
• the maximum putter width is located a max width offset distance from the origin, the minimum putter width is located a min width offset distance from the origin of no more than 130% of a mid-plane distance, a max width vertical plane is located at the maximum putter width, a min width vertical plane is located at the minimum putter width, a min-max width offset is a distance from the max width vertical plane to the min width vertical plane, the min-max width offset is no more than 50% of the striking face width, the center of gravity CG is located between the max width vertical plane and the min width vertical plane, and the mid-plane distance is one-half of the putter length;
• a projection of the center of gravity CG vertically onto the face center horizontal plane produces a projection intersection point located within a CG variation angle of less than 45 degrees, where an apex of the CG variation angle is located in the face center horizontal plane at a point that the shaft axis intersects the face center horizontal plane, and CG variation angle opens symmetrically from the apex about a vertical apex plane containing the apex and parallel to the club head origin X-axis;
• the putter head has an inertia tensor including a Ixx moment of inertia about the CG X-axis, a Iyy moment of inertia about the CG Y-axis, a Izz moment of inertia about the CG Z-axis, a Ixy product of inertia, a Ixz product of inertia, a Iyx product of inertia, a Iyz product of inertia, a Izx product of inertia, and a Izy product of inertia;
• a Ixx-Izz ratio of the Ixx moment of inertia to the Izz moment of inertia is 0.375-0.475;
• an absolute value of the Iyz product of inertia is 2.75-5.5% of the Ixx moment of inertia;
• a forward-upright product is a product of the CGy coordinate and the lean angle, and the forward-upright product is 17.5-53 mm degrees;
• a low-forward product is a product of the CGy coordinate and the Zup value, and the low-forward product is 225-400 mm2;
• and
• a low-forward-lean product is a product of the low-forward product and an absolute value of the lean angle, and the low-forward-lean product is 225-550 mm2·degrees.