A unique safety system for your screwed joints that uses tension instead of friction. The proven "wedge" principle, in accordance with DIN 25201, outperforms all conventional solutions to prevent unintentional loosening due to vibrationPrinciple: The device consists of a pair of washers with an inner face incorporating ramps whose pitch is greater than the thread pitch and an outer face incorporating radial toothing. The washers are positioned in pairs, cam against cam. The washers are positioned in pairs, cam to cam. When the screw and/or nut is tightened, the ridges of the NORD-LOCK washers anchor the surfaces in contact, allowing movement only at the level of the cams. Any rotation of the screw or nut is stopped by the effect of the inclined planes of the washers.