In a golf ball having at least a set of large and small diameter dimples, the large and small diameter dimples are of the same cross-sectional shape in their lower portion. The small diameter dimple (2) has the same shape in cross-sectional view from a depth of 0.01 mm below the dimple (2) edge (3)...http://www.google.co.uk/patents/US5720676?utm_source=gb-gplus-sharePatent US5720676 - Golf ball
