HI70442M is a premium quality 1,500 mg/L (ppm) TDS calibration solution that is prepared against a NIST traceable potassium chloride solution. Hanna TDS solutions have the lot number and expiration date clearly marked on the label and are air tight with a tamper-proof seal to ensure the quality of the solution. Hannas line of TDS calibration solutions have been specially formulated to have an expiration of 5 years from the date of manufacture for an unopened bottle.

• Air tight bottle with tamper-proof seal to ensure quality