TDS solution are produced with high-quality potassium chloride in various concentrations. They are standardized using a conductivity meter calibrated with NIST potassium chloride.Specifications:1382 ppm (mg/L)25 x 20 mL sachetsTDS solution are produced with high-quality potassium chloride in various concentrationsStandardized using a conductivity meter calibrated with NIST potassium chloridePackaging has been designed to keep air and light from damaging the calibration solutions