Stainless steel square nuts are also known as 4-sided nuts. These nuts range in size from ¼ inch to 24 inches. It is made from various material grades like 18-8 stainless steel, A2, A4, and other high-tensile materials. Size can be metric or imperial. The M6 square nut is a metric nut used in hardware, automobile, petrochemical, oil and gas, general engineering applications, and construction.