Golf club head

A hollow golf club head comprising:

• a sole part,
• wherein the sole part has a first groove forming part and a second groove forming part which have a recessed outer surface and a protruding inner surface;
• the first groove forming part and the second groove forming part have a front-back directional length;
• and
• a distance between the first groove forming part and the second groove forming part in a toe-heel direction increases in a direction toward a back of the head;
• the sole part further comprising:
• a plurality of sets of the first groove forming part and the second groove forming part,
• wherein the sole part is absent of any other groove forming parts between the first groove forming part and the second groove forming part of a first set of the plurality of sets, and
• wherein the sole part is absent of any other groove forming parts between the first groove forming part and the second groove forming part of a second set of the plurality of sets.