Miniature precision sapphire and ruby balls for use in medical and chemical pumps as check and metering valves, as ball and roller bearings, and as endoscope lenses and stylus tips are available from Meller Optics Inc. They are second only to diamond in hardness to provide good wear resistance, have a 2000 °C melting point, and are impervious to most chemicals, solvents and detergents. Suitable for applications in medical devices and instruments, these miniature precision balls are offered in 42-in. and metric sizes from 0.1 mm to 0.5 in. in diameter. They can be used as spacers in metrology applications, in flow meters, bar-code readers and fiber optics.