Box Open PH-903 Digital Soil PH Meter Portable Water PH Tester For Aquarium Lab Pool Large LCD screen displays the PH value, easy to read in seconds. Equipped with screw joint extended composite electrode, suitable for direct measurement in small diameter container. High and fast response PH meter, easy to use. Compact and lightweight design, convenient to carry. Suitable for aquariums, aquaculture, hatchery, food processing, laboratories, paper industry, swimming pools and school use.