A waterproof pen-type pH tester from the same family as Muya's other water-quality pens, measuring pH from 0 to 14 alongside live temperature on a backlit display. One-touch automatic two-point buffer calibration keeps setup fast, and the replaceable glass-bulb probe stores safely in its own moisture-filled protective cap between uses. A practical everyday tool for checking drinking water, pool or spa chemistry, aquarium water, and hydroponic nutrient solutions.