How to select calibration weights

1. Confirm the material of calibration weights: 
   Generally speaking, for high-precision scales or low capacity scale/balance, stainless steel calibration weights are best choice. 
   For heavy capacity scales, cast iron calibration weights will be better choice.
2. Confirm the class: High-precision scales need high class calibration weights, normal scales will use common class calibration weights.
3. Confirm the nominal value or sizes: You can choose the calibration weights according to the scale range which need to be calibrated.