DIN 125 / ISO 7089 A4 flat washer are round metal washers made of A4 acid-resistant stainless steel. These washers are designed to distribute the load evenly under screw or bolt connections. They are often used in combination with nuts or screws to provide extra support, reduce pressure points and prevent damage to materials. A4 acid-resistant stainless steel gives excellent corrosion resistance and is suitable for use in humid or aggressive environments.