US Patent 7500924 Golf club head

A hollow golf club head comprises a face portion whose front face defines a club face for striking a golf ball, a sole portion intersecting the club face at the lower edge thereof, at least one groove being provided on an outer surface of the sole portion, the groove extending in a v-shaped formation whose corner portion is smoothly bended and protrudes toward a leading edge of the head, the groove having a ratio (W/L) of a length w in its front-rear direction to a length L in its toe-heel direction being from 0.20 to 1.50 at least partially, and a distance between the leading edge and the corner of the groove being in the range. of from 5 to 30 mm in the front-rear direction.