OIML Class E1 calibration weights are commonly used for calibrating other weight references and are suitable for calibrating high precision balances. They are constructed in piece so there is no method of adjustment. This means they are best used in areas where the environment is stable and careful handling is guaranteed. The uncertainty is guaranteed to be 1/3 the tolerance. For more questions about calibration weights and what kind would be best for you application, please contact us. You can reach us through the livechat, via email at email@example.com, or by calling 616-622-2100.