- Measures pH, TDS, temperature, EC and salinity with a single 5-in-1 meter. - The 5-in-1 meter (also called a pH pen or pH tester) is ideal for testing in hydroponics and gardening, pools and spas, aquariums and reef tanks, water ionizers, drinking water, boilers and more. - Features include 3-point calibration with automatic identification, a water-resistant body, simultaneous temperature display, a sleek design with a large LCD display, Automatic Temperature Compensation ATC, data hold function, and a low-battery indicator. - Benefits include a compact handheld design for easy use, multiple water quality parameters in one tool, accurate readings across temperatures with ATC, and clear results on a large display with a handy data hold and battery alert. - Use scenarios: 1) In hydroponics or gardening, monitor pH, EC and TDS to maintain nutrient balance and healthy plant growth. 2) In aquariums or reef tanks, keep pH and salinity within safe ranges to protect fish and corals. 3) In pools, spas or drinking water systems, test pH, TDS and salinity to maintain water quality and safety.