PH Meter Digital 0.01 High Precision Water Quality Tester with 0-14 Measurement Range for Aquarium Swimming Pool Note: Battery and calibration powder not included. Ideal for household or laboratory use, suitable for testing pH balance of drinking water, pool, aquarium, food projects, RO systems, spa, or hydroponics. Specifications: Measuring range: 0.00–14.00 pH Resolution: 0.01 pH Accuracy: ±0.01 pH Battery: 2 x 1.5V LR44 (not included) Automatic temperature compensation: 0–50°C (32–122°F) Dimensions: 15 x 2.5 x 1.3 cm / 6 x 1.1 x 0.5 inch Net weight: 52g / 1.83 oz Warm Tips: Step 1: Turn on the pH meter and clean the electrode with distilled water. Step 2: Immerse the electrode in pH 6.86 standard buffer solution. Step 3: Press the "CAL" button. Wait until the display stabilizes at 6.86 pH. Step 4: Clean the electrode with distilled water, dry gently, then immerse in pH 4.00 standard buffer solution. Step 5: Press the "CAL" button. Wait until the display stabilizes at 4.00 pH to complete calibration. Step 6: Clean and dry the electrode, then place it in pH 9.18 standard buffer solution. Verify reading is within 9.17–9.19 pH. Instructions for use of pH calibration powder: Calibration powder is a pH standard solid. Dissolve in water to prepare standard solution. Suitable for calibrating any pH meter. Each packet prepares 250 mL of solution. Ensure water is added in the correct ratio to maintain calibration accuracy. Precautions: The pH pen probe is made of glass and is fragile. Avoid impact or collision. Do not attempt to replace the probe if damaged. After use, gently wipe the probe with absorbent paper to remove moisture. Note: The pH meter is factory calibrated. Recalibration is only required in the following cases: 1. After prolonged use post-calibration 2. Frequent electrode usage 3. When high measurement accuracy is required