DIN 9021 round flat washer, 20 x 56 x 4 mm, Article number 90212001. Property class / material: steel, surface finish zinc plated. Round Flat Washer manufactured to DIN 9021. 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. Applications: load distribution and locking under bolt heads and nuts in machine building, structural steel, plant maintenance and marine outfitting.