ISO 7040 hexagon lock nut, M20, sst 720 h, Article number 70401020ZFS720. Property class / material: steel class 10, surface finish zinc flake, silver. Hexagon Lock Nut manufactured to ISO 7040 with ISO metric (M) thread, coarse pitch, fully threaded. Standard parts to the same standard, property class, dimensions and surface finish are interchangeable between manufacturers; confirm the controlling standard revision, any class-society or application approval, and the mating thread before substitution.