Sapphire Ring Jewel and Assembely for Flow Meters, Gauges, Indicators, Watches, Clocks, Potentiometers, Aircraft Instruments Sapphire Window Sapphire Ball ... . Multilayer Anti-Reflectance Coatings Single Crystal Sapphire & Ruby Flow Meters, Gauges, Indicators, Watches, Clocks, Potentiometers, Gyros, Aircraft Instruments