1With automatic temperature compensation that will automatically compensate for the solution temperature of 040 , it can provide you with an accurate and stable reading. 2Suitable for freshwater culture, mariculture, swimming pool, beverage factory, wastewater treatment plant and laboratory. 3Compact pen-shape design, lightweight for mobility, you can test water anywhere to get the purest water. 4High accuracy and quick response: fast to get the testing result and can test the oxygen value for any 0.0 20.0mg/L liquid which you wanna test. 5Adopts the digital screen display with backlight, which is more clear and convenient to read data. Condition: Brand New Item Type: Dissolved Oxygen MeterMaterial: Plastic Measuring Range: Dissolved Oxygen: 0.0- 20.0mg/L Temperature: 040C Basic Error: Dissolved Oxygen: 0.3mg/LTemperature: 1CResidual Current: 0.15mg/L Response Time: 30s (90% response at 20C) Automatic Temperature Compensation Range: 040C Power: 4 x LR44 Button Battery (not included) .w-e-text table td,.w-e-text table th,.wang-edit-text table td, .wang-edit-text table th{border: .5pt solid000;};.w-e-text table,.wang-edit-text table{border: 1px solid000important;}1 x Dissolved Oxygen Meter1 x Electrode3 x Replaceable Electrode Head1 x Instruction1 x Plastic BoxPlease note that the product is without electrode filler.