DS EN 4009:2005 Aerospace Series - Bolts, Double Hexagon Head, Close Tolerance Shank, Medium Length Thread, In Heat Resisting Nickel Base Alloy Ni-Ph2601 (Inconel 718) - Classification: 1550 Mpa (At Ambient Temperature)/650 Degree C Defines the characteristics of double hexagon headed bolts, with close tolerance shank and medium length thread, in NI-PH2601, for aerospace applications.