An acorn nut, also known as a cap nut or crown nut, is a type of fastener that is used to cover the threaded end of a bolt or screw. Its shape resembles that of an acorn or a rounded cap, which gives it its name. Acorn nuts are primarily used for aesthetic purposes and to provide a finished appearance to a threaded connection. They are commonly used in applications where the exposed end of a bolt or screw needs to be concealed or protected.
It's important to note that while acorn nuts provide a decorative cover and help protect the threads from damage, they do not provide the same locking or fastening function as regular nuts or lock nuts. If you need a nut that also provides locking capabilities, you may need to use a separate locking mechanism, such as a washer and a lock nut, along with the acorn nut for the desired aesthetic effect.