Kcl, NaCl and 442 conversions printed on the bottle for ease of use (excluded on 60-ml bottle, but included in insert) temperature corrections are printed on the bottle, with certified values listed in tables and referenced to 25 degree C (excluded on 60-ml bottle, but included in insert) manufactured under ISO 9000 quality guidelines and traceable to NIST standards If unopened, shelf life is 1 year conductivity options range from 1 µs/cm to 200, 000 µs/cm ideal for laboratory and field analysis all Oakton conductivity and TDS standards are traceable to NIST standard reference materials solutions help you calibrate conductivity instruments to ensure accuracy standard values given at 25 degree C use when readings are expected to be around 12.88 MS/cm (12, 880 µs/cm).