M16 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 = 14.1 mm h = 27.5 mm s = 24 mm e = 26.75 mm Thread pitch : 2.00 mm A2 (T304) Grade Stainless Steel