This meter supports a 4.5 V DC supply and the detection range of the meter is about pH:0.01-14.00pH, TDS: 1- 9999ppm at Temperature: -50℃ ~ 70℃ (-58℉~ 158℉) This meter is used to test the pH, the TDS, and the temperature of the water for the aquarium, environment, pools, and also potable water also Ideal for all water.