M20 Hex Nut - A2 Grade A2 stainless steel has good resistance to corrosion except in severe industrial and Marine Condition. Use A4 in a marine environment. Where: e = point to point m = thickness s = across flats d = Thread Thread Pitch - 2.5 mm e - 32.95 mm (min) m - 14.9 mm (min) s - 30 mm d - M20 DIN934