[Testing more accurate and convenient]Hold 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 testing]TDS 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 function]Automatic 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 used]Test 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