Feature:_x000D_ _x000D_ Compact and portable pen design,easy to operate and storage. _x000D_ Large and clear LCD with backlight, easy to read and accurately measuring functions. _x000D_ The tester is made of high quality electronic components to ensure high accuracy. _x000D_ Suitable for water sources, aquariums, hydroponics, swimming pools and other water systems. _x000D_ The resolution of ORP tester is 1 mv, very high sensitivity. _x000D_ _x000D_ Specification:_x000D_ Model: ORP2069_x000D_ Measurement range: 0 - 1999mg/LmV_x000D_ Resolution: 1 mV_x000D_ Accuracy: 5mV_x000D_ Operating voltage: 4*1.5V (AG-13 battery) (No-include)_x000D_ Working temperature: 0- 50_x000D_ _x000D_ Correction: 1 point correction _x000D_ _x000D_ _x000D_ Operation steps:_x000D_ 1. Remove the protective cover._x000D_ 2. Touch the ON/OFF switch lightly and turn on the power supply._x000D_ 3. Put the electrode into the solution under test, shake it gently, and read the display value when the value is stable._x000D_ 4. Touch the "HOLD" button to keep the current measured value. If you need to re-measure, press the "HOLD" button again to automatically remove the holding state._x000D_ 5. After using, press off the switch, clean the electrodes with distilled water, and put a protective cover on them._x000D_ _x000D_ Battery installation:_x000D_ If the display is blurred or not, the battery should be replaced in time. When replacing batteries, the top cover can be switched off and replaced. _x000D_ Pay attention to the polarity of batteries._x000D_ _x000D_ 1. When measuring, shake the instrument gently. Do not let the electrode have bubbles. Otherwise, the measurement results will be affected._x000D_ 2. Instruments should not be adjusted at will, only if they have been used for a long time or are used very frequently, they should be re-calibrated._x000D_ 3. If there are some phenomena such as large error of indication number, indication jumping and indication not returning to zero, we should insert the part below the instrument immersion line into alcohol and shake it for several times to clean the sensor. In low temperature or wet condition, the indication value does not return to zero (the last digit load of the display is less than 2), which will not affect the measurement value._x000D_ _x000D_ Package list:_x000D_ _x000D_ 1 * ORP Tester _x000D_ 1 * Installation tool _x000D_ 1 * User manual _x000D_ _x000D_ Note:_x000D_ The actual product color may deviate from the photo due to light._x000D_ There may be a slight deviation in the measurement of product.