Field of Application: For St 12, St 13, St 14, St 33, St 37, UST 37, RSt 37, St 44, St 50, St 52, other unalloyed steels up to a tensile strength of 510 N/mm2, plus aluminium and other soft metals. The pressed-on washer generates a higher surface pressure, which helps to prevent stress cracks. Advice: Do not use the screw in applications with direct exposure to the weather or in wet rooms with atmospheres containing chlorine gas.