Texas Pneumatic Tools nyloc nuts feature a nylon collar that increases friction on the screw thread to lock fasteners in place to prevent them from loosening due to vibrations or torque. They are ideal for applications where vibrations or motion could loosen or undo the nuts, such as aircraft, automobile and other industrial applications. These economic locking nuts use plastic / nylon inserts located towards the top of the nut for reducing their inner diameter & deforming over the mating thread to capture the bolts or screws and provide resistance against vibrations. They are also used to seal the bolt thread against leakage of oil, water, petrol and other liquids.