Gain Express Pen-type PH Meter Digital Water Quality Tester, 0~14pH for Hydroponics Aquarium Pool Wine Cola Urine Water Tank with Clear LCD with Backlight Function, Portable Pocket Size PortableCompact pen-size pH Meter, light weight for mobility for research, study and personal use Data hold function freezing the desired value andprotective cap that helps reduce contamination 2 points manualcalibration withTemperature Compensation CE RoHS Markingwith Clear LCD and back-light function Test liquids like natural water, drinking water, treated water, waste water, brine solution, sea water and even urine and saliva