Weighing scale usage requirements and precautions:

1. Each scale should come with a set of weights. Within a set, weights of the same nominal mass may have different true values. When weighing, use those without an "*" first to minimize measurement errors.

2. Use tweezers with bone or plastic tips to pick up the weights; do not handle them with your hands directly, and avoid using alloy steel tweezers to prevent scratching the weights.

3. Weights can only be placed inside the weight packaging box or on the weighing pan, and not elsewhere.

4. The surface of the weights should be kept clean, and frequently wiped with a soft bristle brush to remove dust. Any stains can be cleaned with a cloth dampened with alcohol.

5. If the weights have fallen and sustained damage, or if there are signs of oxidation stains and loose markings on the scale, they must be immediately inspected. They can only be used after confirmation of their qualification.

6. Regularly calibrate weights according to frequency of use, usually not exceeding once a year.