Blue Ph Value Test Pen, PH Tester 0.01 High-Precision Water Quality Tester, Measuring Range 0-14 PH pH Meter with a sensitive electrode sensor, pH tester with 0-14.0 measuring range could read accurate pH levels quickly and easily. Accurate pH tester Kit (0.01 Resolution) is accurate that it could test accurately within 0.01 pH. Digital pH meters are perfect for home and laboratory testing pH pen can test pH and is perfect for multiple scenarios perfect for testing water, swimming pools, aquariums, spas, hydroponics, wine and beer. [Easy to use]turn on the switch,put the probe into the water and stir (make the small glass ball fully contact the liquid) and the value can be read when the value is stable. When not in use, please cover the cap. The glass electrode of the ph meter exposed to the air, that make the test error and the value unstable, which directly affect the pH meter working. Colour:Blue Material:plastic Package Contents: 3 x pH test pen Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.