VIVOSUN 3-in-1 soil ph tester can test soil pH, moisture and light value. Also you can know an approximate ph value of some liquid such as wastewater (please note it's not an accurate value. If you need accurate ph value of liquid, recommend to buy VIVOSUN PH Meter). With 1-button operation, you can switch among 3 modes easily. Simply choose the measure mode you would like to apply and insert the sensor probe into the soil about 3/4 in. of the probes, getting the reading instantly. Each tester has 2 sensitive metal probes and a light sensor, showing higher efficiency on testing and precision on readings.