M12 DIN 986 Hexagon Domed Cap Nut with Nylon Insert - A2 Stainless Steel Works in a similar way to Nyloc nuts. The non-metalic (nylon) insert helps to “lock” the nut in place. Sometimes called a prevailing torque type nut Measurements in mm: Thread Size: m = 10.37 mm h = 22.5 mm s = 18 mm e = 20.03 mm Thread pitch : 1.75 mm A2 (T304) Grade Stainless Steel