P. L. Tandon & Co. Manufactures Lab. Model Digital pH Meter. P. L. Tandon & Co. Is an ISO 9001 2000 certified co. Of manufacturing laboratory instruments. The Lab. Model Digital pH Meter Display 3 ½ digit LED Resolution 0.01 pH to 14 pH, 0 to plus/minus 2000 mv, Accuracy 0.01 pH & plus/minus 1 mv, temperature compensation 0 to 100degree C [manual] power supply 230 V 10% Hz supplied with combined electrode, buffer solutions Electrode stand, dust cover.