200,000 umhos Standard-Accuracy at 25 deg C is ±0.25 micromhos for 1, 5, and 10 umhos solutions and ±0.25% for other solutions or the uncertainty shown on the certificate, whichever is greater.
Chemistrys Colorful Clue Lab Activity kit, accompanying teachers guide have been developed by the American Chemical Society through grants from the National Science Foundation and National Institutes of Health, helpful for students