1Used to measure the oxidation reduction potential (ORP) level. 2Dual function, can measure the ORP. 3Compact and portable pen design,easy to operate and storage. 4Waterproof rating IP65, replaceable sensor probe. 5Large and clear LCD with backlight, easy to read and accurately measuring functions. Description: The water quality monitor is the useful tool for testing ORP/TEMP of solution level. It looks like a pen, the portable size is good for carrying. Suitable for water sources, aquarium, hydroponics, laboratory and scientific testing, spas, swimming pools and other water systems. Feature: Used to measure the oxidation reduction potential (ORP) level. Dual function, can measure the ORP. Compact and portable pen design,easy to operate and storage. Waterproof rating IP65, replaceable sensor probe. Large and clear LCD with backlight, easy to read and accurately measuring functions. Suitable for water sources, aquariums, hydroponics, spas, swimming pools and other water systems. Steps: 1. Remove the protective cover. 2. Touch the "ON/OFF" switch to turn on the power. 3. Put the electrode into the solution to be tested, shake it gently, and read the displayed value after the value is stable. 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. 5. After use, press the switch, wash the electrode with distilled water, and put on the protective cover. Precautions: 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. 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. 3: The display value in ORP and air is jumping, it is normal phenomenon that there is no regular change. 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. Speciation: Measuring range: 0~1999mg/LmV Resolution: 1mV Accuracy: 5mV Working voltage: 4 x 1.5V (AG-13 battery) (Not included the battery) Working temperature: 0 C ~ 50 C Correction: 1 point correction Size: 188 x 35 mm / 7.40 x 1.38 inch (appr.) Screw driver length: 95 mm / 3.74 inch (appr.) Package included: 1 x ORP/TEMP Meter 1 x Screw Driver 1 x Manual