M12 Hex Nut - A4 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 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 Where: e = point to point = 21.1 mm m = thickness = 9.64 mm s = across flats = 19 mm d = Thread = M12 Thread Pitch = 1.75 mm DIN934