Digital PH Meter, 0.01 Resolution Pocket Size Water Quality Tester with ATC 0-14 pH Measurement Range for Household Drinking Water, Aquarium, Swimming Pools, Hydroponics (New-Upgraded-Bule-1) HIGH ACCURACY: the pH meter with auto calibration button can automatically identify standard buffer solution of pH4.00, pH9.18, and pH6.86; its high accuracy 0.03pH range of error ensures more reliable results; automatically temperature compensation(ATC) ranges from 050(32F~122F) automatically to ensure accurate readings. EASY TO OPERATE: just press the button to switch power, insert and stir gently in the test solution, then the LCD display with back light get stable pH value and temperature 050(32F~122F) within seconds, no more color charts or messy test strips. PORTABLE FOR WIDE USE: this pen-type instrument has a compact size, weighs only 1.76 oz (50g) that is perfect for outdoor or household use, ideal for testing drinking water, pool, aquarium, spa, or hydroponics. USER'S MANUAL: this product comes along with a detailed instruction about operation and pH calibration correction for your reference.