Diameter: 25mmDiameter 2: 44mmThickness: 4mmMaterial: SteelFinish: PlainHardness: Class 10Type: Flat WasherSpecifications: DIN 125Box of 3.A flat washer is a thin, usually round, plate with a hole in the middle that is normally used to distribute the load of a threaded fastener. USS flat washers have a large, wider body. SAE flat washers are machined to a tighter specification and have a smaller outside diameter.