Annic 0.05ph High Accuracy Pocket Size Digital Ph Meter Tester with ATC and Backlit Lcd, Measure Household Drinking Water (Red) 0.05pH highly accuracy; 0.01 pH resolution; Reliable and quick readings on Backlight LCD Features ATC Automatic Temperature Compensation, Replaceable Electrode for years of reliable test Great for all pH testing applications including aquariums, swimming pools, tap water, beverage et No calibration needed for new units. Easy to calibrate with pH 4 & 6.86 buffer packets included Handheld pen-type design for portability and convenience with carrying case; CE/FCC/ROHS Approved