[Convenience Use] 5 seconds know the water quality, accuracy, faster. This Combo Set of TDS PH EC Temperature. In addition, it has the best price, reliable quality, all make it your first water quality test. [What is the accuracy? ] pH resolution is 0.01pH, accuracy ±0.01pH. TDS: 0~9990ppm, Conductivity: 0~9990us/cm, accuracy: ±2%. It is the same as the big brand resolution in Amazon, but Pancellent test only need half price. [Durable Model] PH Pen have AUTO CALIBRATION function, no need any kind of screwdriver to calibrate the pH tester pen. TDS Pen have Lock auto shut-off function. [Pocket Portable] Small size but suitable for testing the pH balance of drinking water, swimming pool, aquarium, reverse osmosis system, spa, or hydroponics. [Wide Application] Ideal for home and laboratory pH testing, including drinking water, electroplating liquid, boiler water, aquarium water, swimming pool water, photography flushing fluid, well water, deep groundwater, aquaculture, food processing