The digital pH meter provides accurate pH readings with an accuracy of 0.01 pH. the pH pen has a digital backlit LCD screen that is easy to read in the dark. This pH meter automatically adjusts to the water temperature, it can monitor the pH value up and down, no need to care about the temperature of the liquid being measured. Press the "ON/OFF" key to turn on the meter. Place the pH meter electrode in the solution to be tested (not beyond the immersion line), stir gently, and wait for about until the reading stabilizes. Measuring range 0-9999ppm, 0-9999s/cm; Accuracy 2%; Celsius 0.1-80.0C, Fahrenheit 32.0-176.0 Fahrenheit; Note: This meter cannot test seawater. A water pH tester monitors the safety of your home water. Can be used to test the pH balance of drinking water, laboratory pH meters, swimming pools, aquariums, reverse osmosis systems, spas or hydroponics. size: 155 x 31mm Material: Plastic colour: Blue + Yellow + Black Package Contents: 1 x blue tester 1 x yellow tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.