Product description 1.How to use Remove the protective cap.Rinse the electrode with distilled water, and dry it with filter paper. Turn on the meter,immerse the electrode into the test solution. Stir gently and wait for the reading to stabilize. Turn off the meter after use,rinse the electrode and dry it with filter paper. 2.The meter was calibrated before off the factory. Do not need to calibrate the meter when first use. 3.The glass electrode is fragile, treat it carefully. Don't touch it by hard tools or fingers. 4.Please do not immerse the meter into the solution over the "warning line", to avoid damage to the circuit board. 5.If the "cal'(calibration) button is pressed and electrode exposed to air for a long time,calibration is required. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.