M12 Nylon insert lock nut Nyloc type Galvanised Steel DIN985 These are tapped oversized threads to allow for galvanised layer on male thread d = 21.1 mm h = 12 mm m = 8 mm s = 19 mm thread pitch = 1.75 mm Nylon insert can be various colours (Usually black / dark blue). Please ask if colour is important to you DIN985