... Power supply by 1.5 V battery (LR44) x 4 PCs* Pen type digital tds meter, all in one, tds electrode ... school & colleges, swimming pools, water conditionsSPECIFICATIONSDisplayLCD, size : 20 mm x 27 mm. ConsumptionMeasurement Rangetds0 to 9999 ppmTemp.0 to 50 ... ppm , 1 point calibrationOperating HumidityLess than 80% RHDimension188 x 38 mm (electrode included).Weight82 g (electrode included). pen ...