DS EN 3768:2012 Aerospace Series - Nuts, Anchor, Self-Locking, One Lug, Fixed, Reduced Series, With Counterbore, In Heat Resisting Steel, Mos[2] Lubricated - Classification: 1100 Mpa (At Ambient Temperature)/315 Degrees C Defines the characteristics of one lug, reduced series, counterbored fixed anchor nuts, with a self locking feature achieved by forming the upper portion out of round, in heat resisting steel, MoS[2]