M3 A4 Stainless steel penny repair timber mudguard washer DIN 9021 A4 grade stainless steel has a greater corrosion resistance than A2 in certain environments. It is often used for Marine applications especially when coming into direct contact with salt water. Manufactured to the Din 9021 standard Full dimensions: where d1 = inside diameter (hole size), d2=outside diameter (full diameter of whole piece), h=material thickness D1 = 3.2 D2 = 9 h = 0.8 DIN 9021
