A cylindrical, usually metal casing containing the primer and charge of ammunition for firearms. Such a casing fitted with a bullet. A similar piece of ammunition, such as a shotgun shell. A case filled with high explosives, used in blasting. A small modular unit designed to be inserted into a larger piece of equipment: an ink cartridge; a disposable cartridge of caulking compound. A removable case containing the stylus and electric conversion circuitry in a phonograph pickup. A case containing magnetic tape in a reel; a cassette. A case containing a ribbon in a spool, for use in printers and electric typewriters. A lightproof case with photographic film that can be loaded directly into a camera.