PC101 Swimming Pool Water Quality Tester, Professional 2-in-1 pH and CL2 Meter with double-needle display - What it is: a professional 2-in-1 tester for measuring pH and free chlorine (CL2) in water, with a double-needle display for simultaneous readings. - How to use: insert the sensor part, stir the water gently a few times, then wait a few seconds to obtain accurate readings. - Measurement ranges: pH 5.5 to 9.0; CL2 0.5 to 6.0 ppm. - Key advantages: CL and pH values can be freely switched; easy to measure and easy to analyze the relationship between pH and CL. - Design features: probe slot accommodates the probe; extension cord can be stretched for easy use and storage. - Applications: suitable for drinking water tests, swimming pool laboratories, spas, and other environmental water quality measurements. - Additional notes: professional grade tool for reliable water quality testing across various environments.