Class E1 weights are intended to ensure traceability between national mass standards and weights of a lower accuracy class.
Class E2 weights are intended for use in the calibration of weights of a lower accuracy class and for use with weighing instruments of special accuracy class I. Class E2 weights or weight sets have to be accompanied by a calibration certificate.
These weights and mass standards are according to the international OIML R111.
Weights and mass standards intended for use in the calibration of weights of a lower accuracy class and for use with weighing instruments of special accuracy class I and high accuracy class II. They can also be used as control weights and are usually accompanied by a calibration certificate.
These weights and mass standards are intended for use in the calibration of weights of a lower accuracy class and for use with weighing instruments of special accuracy class I, high accuracy class II and medium accuracy class III. They are usually accompanied by a calibration certificate.