ISO 8738 round flat washer, 12 x 20 x 3 mm, Article number 87381201. Property class / material: steel, surface finish zinc plated. Round Flat Washer manufactured to ISO 8738. 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.