It is a type of metal products with internal threads, designed for fixing parts in critical places. Externally, a crown nut looks like a hexagon with vertically cut slots (the number of slots can be different, it depends on the diameter of the threaded connection). The bolt has a special hole, after screwing the nut in it is inserted cotter pin, or it is fixed with a locking wire. As a result of these manipulations, the connection gets additional reliability. And also crowned products are characterized by the increased complexity of manufacturing.