These hexagon nuts and washers are made from a2 stainless steel the hexagonal shape of the nut is designed to be driven by a wrench spanner and provides excellent torque when done so the washer distributes the load of the nut and helps to reduce vibration stainless steel does not corrode rust or stain with water as ordinary steel does but despite the name it is not fully stain proof most notably under low oxygen high salinity or poor circulation environments stainless steel is used where both th