A4 thin hex nut (lock nut) DIN 439 is manufactured according to the DIN 439 standard. The nut is made of A4 acid-resistant stainless steel, which gives excellent corrosion resistance. The nut has a low profile, and this type of nut is especially suited for applications where limited space is available. The A4 nut is typically used in various applications where a low nut is needed to achieve a tight joint or where space is limited.