BS 4929-2 self-locking nut is a nut that is screwed together with a bolt or a screw to act as a fastening part. It is a kind of original that all production machinery must use. Threads, lock nuts and screws of the same size can be connected together.
BS 4929-2 - 1973 Unified Inch Series Steel Hexagon Prevailing-Toyque Type Nuts
| Legend | Making |
| P=pitch | Carbon Steel:6,8,10,12 |
| K=height of the nut | Thread:6H |
| D=the nominal diameter of the thread | Surface:BLK,ZP,HDG,etc |
| E=The length of the diagonal | |
| S=The length of the flat |