Features: Easy to Use: Simply immerse the pH meter electrode in the solution to be tested, and readings are quickly displayed on a large LCD display. Wide Application: Ideal instrument for aquariums, the fishing industry, swimming pools, spas, school laboratories, food & beverage, drinking water, and more. Auto Calibrated: Features built-in calibration with 2 buffer powders. Just press a button to complete calibration. This pH meter is factory calibrated and ready for immediate use. Fast and Accurate Results: Eliminates the need for color charts and test strips. Resolution: 0.01 pH, Accuracy: ±0.01 pH. Compact Portable Design: Pocket-sized pH meter that is lightweight and compact. Easily fits in your bag or pocket for convenient portability. Specification: Display: LCD Digital Accuracy: ±0.01 pH Resolution: 0.01 pH Operating Temperature: 0~60°C Measuring Range: 0.00~14.00 pH Probe Type: Precision glass bulb electrode Power Supply: 2 x 1.5V LR44 Batteries (Not included) Instructions: Step 1. Remove protective cap. Step 2. Rinse the electrode with distilled water and blot dry with filter paper. Step 3. Turn the meter on by pressing the ON/OFF button. Step 4. Immerse the pH meter electrode in the solution to be tested (do not exceed the immersion line). Step 5. Stir gently and wait approximately 30 seconds until the reading stabilizes. Step 6. After testing, rinse the electrode with pure water and turn the meter off by pressing the ON/OFF button. Step 7. Always replace the protective cap after use. Calibration Instructions: 1. Turn on the pH meter. 2. Dissolve each buffer powder in 250 mL of distilled water. 3. Immerse the electrode into the pH 6.86 buffer solution (at 25°C). 4. Press and hold the CAL button for 5 seconds, then release. The display will flash 6.86. Wait until the display stops flashing. 5. Rinse the electrode with distilled water and blot dry with filter paper. 6. Immerse the electrode in the pH 4.00 buffer solution. 7. Press and hold the CAL button for 5 seconds, then press and release a second time. The display will flash 4.00. Wait until the flashing stops. 8. Rinse and dry the electrode again. 9. Return the electrode to the pH 6.86 solution to verify calibration. If readings are incorrect, repeat the calibration process. 10. If the test solution is expected to be above pH 7.0, use pH 6.86 and 9.18 buffer solutions for calibration following the same steps. Package Includes: 1 x pH Detection Pen Note: 1. Due to differences in monitor displays and lighting, the actual color of the item may vary slightly from the images shown. 2. Please allow 1–3 cm measuring deviation due to manual measurement.