DIN 982 hexagon lock nut, M20, en 10204 3.1 certificate, Article number 9821020CDELSI. Property class / material: steel class 10, surface finish zinc flake, silver. Hexagon Lock Nut manufactured to DIN 982 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.