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, swimming pools, household tap water quality testing. Specifications: Shell Material: Plastic Main Color: Yellow, Grey, Red as picture (Optional) Range: 0~9990ppm Accuracy: +/-2% Battery: 2 x 1.5V Button Cell Batteries (not included) Size: Approx. 15.5 x 3 x 1.6cm / 6.1 x 1.1 x 0.6in 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 Package Included: 1 x Water Quality Tester (without battery)