Flange nut， One end of it has a wide flange that can be used as an integrated gasket. This is used to distribute the pressure of the nut onto the fixed component, thereby reducing the possibility of component damage and making it less likely to loosen due to uneven fastening surfaces. These nuts are mostly hexagonal in shape, made of hardened steel, and usually coated with zinc on the surface. In many cases, the flange is fixed and rotates with the nut. The flange can be serrated to provide locking action. The serrations form an angle so that the nut does not rotate in the direction of loosening the nut. Due to serrations, they cannot be used with washers or on scratched surfaces. Sawtooth helps prevent the vibration of the nut from moving the fastener, thereby maintaining the holding force of the nut.