The lugs are secured closed by a salt-blued or parkerized and knurled carbon steel ferrule. Cartridge (ferrule) fuses have a cylindrical body terminated with metal end caps. A paintbrush is usually made by clamping the bristles to a handle with a ferrule. FC connectors' floating ferrule provides good mechanical isolation. The ferrule is broken off of the fastener after the weld is completed. Modern connectors typically use a "physical contact" polish on the fiber and ferrule end. Compression of this ferrule also results in deformation of the copper tubing. Some compression connectors may never be reused, such as a ferrule ring type. They are generally larger than screw-type fuses, and have ferrule cap or blade contacts. The name "FC" is an acronym for "ferrule connector" or "fiber channel". The European taper widens continually and smoothly from the ferrule toward the joint. If the nut is overtightened the ferrule will deform improperly causing the joint to fail. By placing the end of the stranded wire in a ferrule, the strands stay together. A metal ferrule holds the hair-spreading wedge and the shell slide in place. The ferrule can also help preserve the hermetic seal of the luting cement.