Thompson makes pebble heads in both 64 hole and 54 hole formats. Size are read with the number of holes preceding the dash and the diameter of the holes following the dash. Heads sized 62-72/74 and 54 74/76 have holes sizes of both diameters on the same head. Heads in sizes 64 - 70 and 64-71 are commonly used on arena ice. All other size combinations are suitable for competition ice making.