Bell metal is a hard alloy used for making bells and related instruments, such as cymbals. It is a form of bronze with a higher tin content, usually in approximately a 4:1 ratio of copper to tin (typically, 78% copper, 22% tin by mass). The higher tin content increases the rigidity of the metal, and increases the resonance. It also has industrial uses, being specified for valve bodies, piston rings, bearings, and bushings