DIN 440-R round flat washer, 5.5 x 18 x 2 mm, Article number 440RA4055. Made in stainless steel a4. Round Flat Washer manufactured to DIN 440-R. 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.