Description Features in-built calibration with 2 buffer powders(included).Just press a button to finish the calibration. This pH meter is factory calibrated. Users can use it directly. Fast and Accurate Results: No need to work with those annoying color charts and test strips.Resolution: 0.01 pH, Accuracy: 0.01 pH Compact Portable Design: Pocket fitting pH meter thats also lightweight and compact. Total concealed fit in your bag or pocket for easy, casual carrying. Item Describe: 1. Display: LCD Digital 2. Accuracy: 0.01 3. Resolution: 0.01 4. Operating Temperature: 0~60C 5. Measuring Range: 0.00~14.00 6. Probe Type: Precision glass bulb electrode How To Use : 1. Remove protective cap. 2. First rinse the electrode with distilled water and suck it with filter paper. 3. Turn the meter on by pressing ON/OFF key. 4. Immerse the pH meter electrode in the solution to be tested (should not be over the immersion line). 5. Stir gently and wait around 30 seconds till the reading stabilizes. 6. After finishing, clear the electrode with pure water, turn the meter off by pressing ON/OFF key. 7. Always replace the protective cap after use. Steps : 1. Turn on PH meter 2. Disolve each buffer solution in 250ML of distilled water 3. Immerse the electrode into the PH 6.86 solution,(under the temperature of 25) 4. Press the CAL(calibration)button for 5 seconds and release -Display will start flashing 6.86 -Wait until the display stops flashing. Rinse the electrode with distilled water and dry it with filter paper. 5. Immerse the electrode in PH 4.00 solution, -PressCALbutton for 5 seconds,then press and release immediately second time -Reading will start flashing 4.00 -Wait until display stops flashing Rinse and dry the electrode with distilled water as before. 6. Place the meter back to the buffer solution to test calibration.If incorrect,please repeat the calibration 7. If approximate PH of your test solution is known to be above 7.0,calibrate the meter using 6.86 and 9.18 solution. To do this,please follow the calibration chart,The third step is the calibration method for 9.18 point. Package include: 1pc * pH Meter 1pc * Instruction Manual This item come without retail box and battery, and it need LR44