Legal for trade scales are required to ensure fairness to both buyer and seller, and they are sealed at the point of manufacture to pass audits by applicable regulatory bodies.

Scales or Balances calibrated in a factory in China, Taiwan, Japan, Europe, may not read 100% accurately in the UK due to differences in local gravitational pull, shipping bumps, and temperature changes. Gravity varies slightly across the Earth, meaning precision or trade-approved scales should always be recalibrated for their final location.