DS EN 4498:2005 Aerospace Series - Bolts, Large Bihexagonal Head, Close Tolerance Normal Shank, Medium Length Thread, In Heat Resisting Nickel Base Alloy, Passivated, With Aluminium Pigmented Coating - Classification: 1550 Mpa (At Ambient Temperature)/315 Degree C Defines the characteristics of bolts, large bihexagonal head, close tolerance normal shank, medium length thread, in heat resisting nickel base alloy, passivated, with aluminium pigmented coating.