HM Digital C342 TDS and EC Calibration Solution, 342 ppm (NaCl), 90 ml Volume
HM Digital TDS-3 Handheld TDS Meter With Carrying Case, 0 - 9990 ppm TDS Measurement Range, 1 ppm Resolution, +/- 2% Readout Accuracy
HM Digital 1000ppm TDS Calibration Solution
HM Digital TDS-4 Pocket Size TDS Tester Meter Without Digital Thermometer, 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 2% Readout Accuracy