Usage: Capacity standard balls are in accordance with the "Standard Glass Measuring Instrument Verification Procedures", used for verifying titration tubes, pipettes, volumetric flasks, graduated cylinders, beakers, etc. of glass measuring instruments. The complete set consists of 31 pieces ranging from 0.5 to 1000 ml. The flat-head standard balls are quantitative measuring instruments for quantitative measurement, while the pointed-head standard balls are quantitative measuring instruments for quantitative filling. Capacity standard balls are widely used in scientific research, chemical industry, medical colleges and universities, metrology technology research departments, and factory and mine enterprises. They are the preferred measuring instruments for scientific research departments and metrology verification departments when conducting verifications of glass measuring instruments.