ISO 4017 hexagon head screw, M12 x 20, Article number 4017812020GEO500B. Property class / material: steel 8.8, surface finish zinc flake, silver. Hexagon Head Screw manufactured to ISO 4017 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.