sensitivity alloy probe and glass electrode deliver accurate water quality measurements, with automatic temperature compensation to reduce errors across varying temperatures. Backlit display automatically activates when the unit powers on, ensuring clear readings in dim conditions. 4in1 measurement in one pen: temperature, TDS, EC, and pH readings to meet a range of detection needs. Widely applicable: suitable for domestic water, swimming pools, aquaculture, environmental water quality, agricultural water, fish tanks, greenhouse irrigation, barreled water, community water stations, and more. 4in1 pen design provides versatile monitoring in a single instrument, simplifying testing and reducing the need for separate devices. 23 practical use scenarios: Home drinking water: routinely check water quality to ensure safety and suitability for family use. Swimming pool maintenance: monitor pH, EC, and TDS to balance sanitizers and ensure comfortable, sanitary water. Aquaculture and fish tanks: maintain appropriate pH, temperature, EC, and TDS levels to support healthy aquatic life and stable water conditions.