Nylock Nuts M3 - M5 DIN 985 ~ Nylock Nut A2 Grade Serrated Flange Nuts M4 & M5 DIN 6923 ~ Serrated Flange Nut A2 Grade Nut & Washers Combo M3 & M4 DIN 985/125 ~ Nylock Nut & Washer A2 Grade Form A Washers M3 & M4 DIN 125 ~ Form A Washer A2 Grade Nylock Nuts and Form A Flat Washers Nylon insert lock Nuts are A2 grade stainless steel with the recognised standard - DIN 985. Form A Washers are A2 grade stainless steel with the recognised standard - DIN 125. Serrated flange Nuts are A2 grade stainless steel with the recognised standard - DIN 6923. A2 grade of stainless steel has excellent corrosion resistant properties.