DIN EN 2922:1993-10

Aerospace series - Nuts, hexagon, plain, reduced height, reduced across flats, in heat resisting steel, passivated, left hand thread; Classification: 600 MPa (at ambient temperature)/650 °C

Aerospace series; nuts, hexagon, plain, reduced height, reduced across flats, in heat resisting steel, passivated, left hand thread; classification: 900 MPa (at ambient temperature)/650 °C