Bolt Base 12mm A2 Stainless Steel Internal Toothed Shakeproof Washers Tooth Lock Shake Proof Washer DIN 6797J M12 - 50 Corrosion Resistant A2-70 Stainless Steel Toothed Shakeproof Washers- DIN 6797 Approx Dimensions- Inner 13mm, Outer 20.5mm, Thickness 1mm Ideal For A Wide Range Of Applications