6 in 1 Water Quality Tester High Accuracy Portable TDS EC COD Meter Water Quality Test Pen Item Type: Water Quality Tester Size: Approx. 157 x 37 x 14mm / 6.18 x 1.46 x 0.55in Battery: AAA x 2 (not included) Detection Functions: Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Total Dissolved Solids (TDS), Ultraviolet Absorption Value (UV275), Electrical Conductivity (EC), Temperature (T) Calibration: Long press the button in measurement mode to enter the calibration interface. The screen will prompt "Insert the instrument into distilled water, press the measurement button to calibrate!". Insert the instrument probe into distilled water and press the button to start calibration. After calibration is completed, it will prompt "Calibration success!" and return to the measurement page. Measurement: Insert the instrument probe into the sample water, press the button to measure. After measurement, the default 3 parameter mode of the instrument will display COD, TOC, and TDS. Setting it to 6 parameter mode will display COD, TOC, UV254, TDS, EC, and temperature. The instrument will also score the water quality based on the test data and display different backlit colors on the screen according to the water quality judgement, Poor red, Fair yellow, Good green, Excellent blue. Settings: Long press the button for 3 seconds when the instrument is off to enter the main menu. There are 4 sub options: Language, Display, Calibration, Exit. Use the button to choose the option and press the button to confirm the selection. Weight: Approx. 114.00g / 4.02oz