Calibration Weights are used to check the reading of scale, to make sure it is still accurate. They used when calibrating a scale.
While the calibration states how a scale behaves, adjustment of the scale changes its behavior. What it dose is a set of operations carried out on a scale so that it provides prescribed indications corresponding to given values of a quantity to be measured.
Therefore, adjusting a scale means modifying its indications in a way that allows them to correspond – as much as possible – to the quantity values of the measurement standards applied.
ANSI/ASTM Class 0 Reference Weights - Used as a primary reference for calibrating other reference standards and calibration weights. Class 0 weights should be used in metrology laboratories where the stability of the environment and careful handling are assured. ASTM Class 0 reference weights and weight sets should be used in secondary calibration labs, manufacturing quality control, state laboratories, or similar weight calibration environments. Class 0 weights can be used to calibrate analytical balances, Class I and Class II laboratory balances, and ASTM Class 4, 5, and 6 weights. ASTM Class 0 weights are equivalent to OIML Class E2 weights.