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 Usage Steps: Step 1: Turn on the pH meter. 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 and dry gently. Immerse in pH 4.00 standard buffer solution. Step 5: Press the "CAL" button. Wait until the display stabilizes at 4.00 pH. Calibration complete. Step 6: Clean and dry the electrode. Immerse in pH 9.18 standard buffer solution. Verify reading is within 9.17–9.19 pH. Instructions for 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. Note: Add water in the correct ratio to ensure calibration accuracy and minimize error. Precautions: The pH pen probe contains glass and is fragile. Avoid impact or collision. Do not attempt to replace if damaged. After use, gently wipe the probe with absorbent paper to remove moisture. The pH meter is factory calibrated. Re-calibration is required in the following cases: 1. After prolonged use since last calibration 2. Frequent electrode usage 3. When high measurement accuracy is required