A Nyloc nut, also referred to as a nylon-insert lock nut, polymer-insert lock nut, or elastic stop nut, is a kind of lock nut with a nylon collar that increases friction on the screw thread. The screw thread does not cut into the nylon insert, instead, the insert deforms elastically over the threads as tightening pressure is applied. The nylon insert locks the nut against the screw as a result of friction, caused by the radial compressive force resulting from the deformation of the nylon. The Nylon is heat and chemical sensitive. Please check the suitability regarding your job. Alternatively, Conelock nuts and Lock nuts, which are located in the BOLTS ONLINE Nuts Category. Important note - Galvanised Nyloc Nuts are slightly oversized to allow for the extra Coating of Microns. When designing and detailing tapped holes, the increased thickness is important to take note of.