DS EN 3444:2006 Aerospace Series - Bolt, Large Bihexagonal Head, Close Tolerance Normal Shank, Medium Length Thread, In Heat Resisting Nickel Base Alloy, Passivated - Classification: 1250 Mpa (At Ambient Temperature)/650 Degree C Defines the characteristics of bolts, large bihexagonal head, close tolerance normal shank, medium length thread, in heat resisting nickel base alloy, passivated.