DIN 439 LH Hex Nut A2-035 Left-Hand Thread

Material stainless steel A2. Property class A2-035. Metric left-hand thread pitch (LH). Stainless steel A2, good corrosion resistance.

Special nuts are nuts whose design, use, dimensions, or other characteristics differ from a standard hex nut.
Examples include low nuts (thin nuts), flange nuts, castle nuts, rivet nuts, square nuts, diamond-shaped nuts, sheet metal nuts, and weld nuts.
Materials include uncoated or zinc-plated steel (bright zinc, Zn, zinc), stainless steel (A2), and acid-resistant stainless steel (A4).
Choosing the right nut? The rule is that the nut’s hardness, material, and coating should be at least equal to those of the fastener used (bolt, screw).