Testing more accurate and convenientHold automatic locking function makes the water quality pen easily to read and record; automatic temperature compensation mode to water quality test more accurate; accuracy error range is as low as 2%. Wide range testingTDS meter measuring principle is to measure the electrical conductivity of water and indirectly reflects the TDS value. TDS ranges from 0~9990ppm(parts per million). Auto-off functionAutomatic power-off function allows it to power off after 5 minutes without any operation in order to save power. It supports hold function that can save measurement results for easy reading and record. Pocket Portable 6.1 * 1.18 * 0.71in, the water quality pen ultra compact and lightweight to carry on,even can be packed on your pocket or bag and goes anywhere. Wide usedTest the impurities in water such as some elements of soluble salts, ionic organic compound, heavy metal ion, etc. The TDS meter tester can be used in: water purifiers and filters, food (vegetable,fruits) drink quality monitoring, pools and spas, aquariums, hydroponics etc. Specifications: TDS Range: 0-9990ppm Temperature Range: 0-99 Accuracy: 2% color: as the picture shown Battery Type: 2 * 1.5V LR44 Button Batteries(included) Size: Approx. 15.5*3*1.8cm/6.1*1.18*0.71in Weight: Approx. 70g Package Included: 1 * TDS Tester