Water Purity Tester: Digital TDS Meter Water Filter Quality Measuring Machine Portable Pocket Handheld Pen Type Hydroponic PPM Indicator + Hold Function + Temp Display for RO UV UF Mineral Water Purifiers Filter The LCD digital TDS meter tester is used for testing the filter water quality purity, to check the performance of your water. In order to make sure you always drink pure and safe water, the TDS meter tester is recommended for every family. Features: The TDS meter tester can be used in water purifiers and filters, food (vegetable, fruits) & drink quality monitoring, pools and spas, aquariums, hydroponics etc. Hold function: Saves measurements for convenient reading and recording. Auto-off function: Turns off meter after 10 minutes of non-use to conserve batteries. Press "TEMP" button can shift temperature meter between Fahrenheit degree and centigrade degree. Measures Range: 0-9990ppm, with a resolution of 1ppm. From 1,000 to 9,990ppm, the resolution is 10ppm, indicated by drinking x 10image, factory calibrated. Applicable industries: water laboratories, CDC, the aquaculture industry, hospitals, and swimming pools, household tap water quality testing. Specifications: Condition: 100% Brand New Shell Material: Plastic Range: 0~9990ppm Accuracy: +/-2% Battery: 2 x 1.5v LR44 Button Cell Batteries (included) Size: Approx. 15.5 x 3 x 1.6cm / 6.1 x 1.1 x 0.6in Package Included: 1 x Water Quality Tester 1 x Case 1 x English Manual Note: > Please allow 0~1inch error due to manual measurement. Thanks for your understanding. > Please refer below standard for testing water 0~50ppm --------- High Purity Water 50~100ppm --------- Pure Water 100~300ppm --------- General Pure Water 300~600ppm --------- The water will have incrustation scale 600~1000ppm --------- Bad Taste Water Above 1000ppm --------- The water is not suitable for drinking