Feature: <br> <br> Compact and portable pen design,easy to operate and storage. <br> Large and clear LCD, easy to read and accurately measuring functions. <br> The tester is made of high quality electronic components to ensure high accuracy. <br> Suitable for water sources, aquariums, hydroponics, swimming pools and other water systems. <br> The resolution of ORP tester is 1 mv, very high sensitivity. <br> <br> Specification: <br> Model: ORP-169 <br> Measurement range: -1999 - 1999mv <br> Resolution: 1 mV <br> Accuracy: 5mV <br> Operating voltage: 4*1.5V (AG-13 battery) (No-include) <br> Working temperature: 0- 50 <br> <br> Correction: 1 point correction <br> Product dimension:188*35*35mm / 7.4*1.4*1.4in <br> Weight: 290g / 10.2oz <br> <br> Steps: <br> 1. Remove the protective cover. <br> 2. Touch the "ON/OFF" switch to turn on the power. <br> 3. Put the electrode into the solution to be tested, shake it gently, and read the displayed value after the value is stable. <br> 4. Touch the "HOLD" button to keep the current measured value. If you need to re-measure, press the "HOLD" button again to automatically release the hold status. <br> 5. After use, press the switch, wash the electrode with distilled water, and put on the protective cover. <br> <br> Precautions: <br> 1: There is a white crystalline salt around the electrode, which is a normal phenomenon of the ORP electrode. Only when the electrode is immersed in clean water, it dissolves and disappears. <br> 2: When testing the ORP value, it usually takes about a few minutes to about 10 minutes. Wait for the value to stabilize and jump very slowly or read the displayed value as the measured value. <br> 3: The display value in ORP and air is jumping, it is normal phenomenon that there is no regular change. <br> 4: After use, please turn off the power, wash the electrode with pure water or distilled water, use a soft tissue to dry the water and put on the protective cover. <br> <br> <br> Package list: <br> <br> 1 * ORP Tester <br> 1 * Installation tool <br> 1 * User manual <br> <br> Note: <br> The actual product color may deviate from the photo due to light. <br> There may be a slight deviation in the measurement of product.