Oxidation-Reduction Potential (ORP) is a measure of the ability of a solution to either oxidize or reduce another substance. The ORP value indicates the redox potential of a solution and is expressed in millivolts (mV). An ORP meter is a specialized device used to measure this redox potential.The instrument features a waterproof enclosure with an IP55 protection rating. The electrode is replaceable.The device includes a data lock function to assist in measuring and recording stable data. This ORP meter can measure negative potential (O.R.P).Advanced technology and components have been used in its design, significantly reducing its size and cost, while maintaining quality. This makes the ORP meter ideal for applications such as functional energy water purifiers and negative potential energy cups where ORP measurement is required.Main Technical Specifications:- Measurement Range: 0 - 1999 mV- Resolution: 1 mV- Accuracy: 5 mV- Power Supply: 4 x 1.5V batteries (not included)- Operating Temperature: 0 - 50C- Calibration: 1-point calibrationInstructions:1. Remove the protective cover.2. Press the "ON/OFF" switch to turn on the device.3. Place the electrode in the test solution and gently shake until the display stabilizes.4. Press the "HOLD" key to lock the current measurement. To measure again, press the "HOLD" key to release the hold function.5. After use, turn off the device, rinse the electrode with distilled water, and place the protective sleeve.Battery Replacement: If the display becomes dim or unclear, replace the batteries. When replacing, unscrew the battery cover and install batteries, ensuring correct polarity.Calibration Procedure:1. Soak the electrode in distilled water for several hours.2. Place the electrode in the calibration solution and gently stir.3. Use a screwdriver to adjust the trimmer until the display reads 265 mV.4. Rinse the electrode with distilled water and dry with filter paper.Color: White and Green Material: ABS and electronic components Dimensions: 18.8cm x 3.5cm x 3.5cm Package Contents:- 1 x 169E ORP Tester - 1 x English Manual Note: Slight color differences may occur due to lighting or display settings. Measurement tolerance is within 1-3cm.