It's not only ideal for household or laboratory use, also suitable for testing pH balance of drinking water, pool, aquarium, food Project, RO system, Spa, or hydroponics. Specifications: Measuring range: 0.00-14.00 pH Resolution: 0.01 pH Accuracy: 0.01 pH Batteries: 2X 1.5V LR44 (not included) Automatic temperature compensation: 0-50Centigrade(32-122It) Dimensions: 15x2.5x1.3cm/6x1.1x0.5 inch Package Includes1PC Warm tips It STEP 1: Turn open pH meter, Clean the electrode in distill water It STEP 2: Immerse the electrode in pH 6.86 standard buffer solution It STEP 3: Press the "CAL" button. Wait until the display digital is 6.86pH and steady It STEP 4: Clean the electrode in distill water and dry it, immerse the electrode in Ph 4.00 standard buffer solution It STEP 5: Press the "CAL" button. Wait until the display digital is 4.00pH. Then complete pH 4.00 calibration It STEP 6: Clean electrode and dry it, put the meter into PH 9.18 standard buffer solution. Check if reading is correct between 9.17-9.19pH Instructions for use of PH calibration powder: Calibration powder: pH standard solid substance. It can be used after adding water. Suitable for the calibration of any type of ph meter. Each package can prepare 250ML standard solution. (Be sure to add water according to the required ratio, otherwise it will affect the accuracy of the calibration and increase the error) Precautions: Please note that the PH pen probe is a glass product and is a fragile product. Please do not collide with things. Once the damage is not replaceable, you must protect the probe. After use, use absorbent paper to gently absorb the water on the probe. Matters needing attention: PH meter has been calibrated before delivery, the buyer does not need to re-calibrate after receiving the goods In the following cases, the PH meter must be re-calibrated: 1. Has been used for a long time after calibration; 2. Special electrode use Frequently; 3. The measurement accuracy requirements are relatively high.