Item Type: ORP169F Meter Pen Material: Plastic Measurement Range: 0 - ±1999mg/LmV Resolution: 1mV Accuracy: ±5mV Operating Temperature: 0 - 50 Celsius Battery:4*1.5V (AG-13) Included Waterproof: Yes Dimension: 188mmx35mmx35mm Colour:As Shown Material:ABS Operation: 1. Remove the protective cap. 2. Frist clean the electrode with distilled water,and suck it with filter paper. 3. Press the OFF/ON key to switch power. 4. Immerse the meter electrode in solution up to the immersion level.Under no circumstances immerse above display level. 5. Stir gently and wait for the reading to stabilize. 6. After use, switch off it,use the distilled water clean the electrode and replace the protective cap. Package Contents: 1 x ORP169F Meter Pen Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.