YY-400 / YY-400N is a newly developed high-precision multifunctional water quality tester capable of measuring pH, ORP, hydrogen ion concentration, and water temperature. Automatic temperature compensation from 0 to 60°C ensures updated and reliable measurement data. Designed for accuracy, ease of use, and portability, this tester is ideal for monitoring water quality in various environments. Suitable for pH, ORP, hydrogen ion concentration, and temperature testing in household and laboratory applications, including swimming pools, ponds, beer, kombucha, aquariums, hydroponics, laboratories, and food processing. 1. pH Range: 0.01–14.00 pH Resolution: 0.01 pH Accuracy: ±0.05 pH 2. ORP Range: –999 to +999 mV Resolution: 1 mV Accuracy: ±2 mV 3. H2 (Hydrogen Concentration) Range: 0–2400 ppb (0.001–2.400 ppm) Resolution: 2 ppb / 0.001 ppm Accuracy: ±10 ppb / ±0.01 ppm 4. Temperature Range: 0.1–60.0°C (32.0–140.0°F) Resolution: 0.1°C / 0.1°F Accuracy: ±0.5°C (±0.9°F) Dimensions: 183 x 37 x 37 mm Material: Plastic Color: Black and white Package Contents: 1 x Digital Water Quality Tester Note: The package includes only the items listed above. Other accessories are not included. Lighting and display settings may cause slight variations in the color of the product as shown in images. Measurement tolerance is ±1–3 cm.