Engine manufacturers use different types of drilling patterns. Four data points are necessary:
| A | number of holes |
| B | diameter of screws (in mm) |
| C | diameter of the circle on which the holes sit |
| D | diameter of the center hole |
It reads as follows: 6M8d75 = 6 screws with a diameter of 8 mm, placed on a circle with a diameter of 75 mm.

Center hole = 25 mm
Standard drillings for 2-, 3-, 4- and 6-blade models:
Optional drillings (extra charge), for 2-blade only:
Standard drillings (see drawings below):


