DIN 65529
DIN 65529 Aerospace series - Nuts, bihexagonal with flange and MJ-thread, deep counterbore, self-locking, steel, class: 1250 MPa/235 °C
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 10/01/2005
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 10/01/2005