Nylon lock nut is a round nut, and in its outer open four small slot, you can use the crescent wrench screw on the stud, the lock nut should be equipped with a shaft Washer, it can be used to make the small groove on the stud and its peripheral groove relative to the fixed, to prevent its loose.
Bolt thread on the nuts embedded in the nylon extrusion, making the nylon deformation, after installation, the nylon and thread completely squeeze contact, the extruded nylon to the bolt A lot of resilience, increased friction, so that the bolt is not easy to loose.