1. What is anti-loosening lock nut?

The anti-loosening lock nut uses a unique 30° wedge thread technology, preloaded and locked internal (female) thread. 

It can resist lateral vibration, which cause thread loosening. Compared with the standard thread,  it has a uniform load,and no need  any other locking devices: such as locking washer,thread glue, stringing steel wire, rivet , pin ..etc.  Its locking function is entirely dependent on the thread form.