Meller Optics Inc. has introduced a line of sapphire and ruby balls in 42 sizes, both inch and metric, ranging from 0.005 in. (0.127 mm) to 0.5 in. (12.7 mm) in diameter. Designed for use as lenses in fiber optic, laser diode and high wear- resistance applications, and as check valves in chromatography equipment, they have surface finishes of 21-10 scratch-dig or better. The balls exhibit Moh 9 hardness and high sphericity.