https://www.bkneddy.com/eddy-current-testing-equipment/bolt-vortex-sorter-bknfx-11.html Bolt: Mechanical parts, cylindrical threaded fasteners with nuts. A type of fastener consisting of a head and a screw (a cylinder with an external thread) is required to be fitted with a nut for fastening the two parts with through holes. This type of connection is called a bolted connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.