This European standard specifies the characteristics of hexagonal plain nuts@ reduced height@ normal across flats@ in aluminium alloy@ anodized@ for aerospace applications. Classification: 450 MPa1)/120 ??). 1) Corresponds to the minimum tensile stress which the nut is able to withstand at ambient temperature without breaking or cracking when tested with a bolt of a higher strength class. 2) Maximum temperature that the nut is able to withstand@ without permanent alteration to its original characteristics@ after ambient temperature has been restored. The maximum temperature is conditioned by the material.