M20 Hex Nut - A2 Grade - Left Hand Thread Threads are left hand and these nuts tighten anti clockwise, the opposite way to standard nuts, they do not fit standard bolt 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 - Left Hand DIN934