Description: Wide Use: Ideal for Household or Laboratory Use, Suitable for Testing Ph Balance of Drinking Water, Pool, Aquarium, Ro System, Spa, or Hydroponics; Appropriate for Wide Range of Applications Fast and Accurate: Ensure Your Pool, General Hydroponics Ph or Even Drinking Water Has a Perfect Ph Balance and Safe for Use with Tester Precision Ph Accuracy. Tester Has a Sensitive Sensor to Read Accurate Ph Levels. Auto Calibration: The Ph meter has an Auto Temprature Compensation Feature That Adjusts to Water Temperatures and Water Quality to Give Ph Readings Almost Instantly. Specification: Measuring range:0~±1999mg/LmV Resolution:1mv Accuracy: +- 5mv Working voltage:4*1.5V Power Supply: AG-13 battery (Not Included) Correction:1 point correction Size:188mm*35mm*35mm Package Includes: 1 piece ORP Water PH Test Note: Operation steps: 1.remove the protective cover 2.touch the :ON/OFF" switch power 3.place the in the test solution and gently shake until the display shows the value read after a stable value 4.touch the "Hold" button,then keep the value of the current measurement.if you need to remeasure,then click the "Hold" key,the automatic lifting of the state. 5.after use,press the switch off,clean the with distilled water,put on protective sleeve. Note:there is a white crystal staff around the ,which is the normal phenomenon of ORP .