Calibrates TDS/PPM/EC meters. It is rated a 1000 ppm for meters requiring the NaCl solution calibration. Those meters requiring a KCL solution it is rated at 1060 ppm, those needing a "442" solution it reads 1450 ppm and for EC meters it reads 2000. You just need to know what type of solution your meter requires. It has a 6 month shelf life after opening.