Feature: 1. With automatic temperature compensation that will automatically compensate for the solution temperature of 0‑40 ℃, it can provide you with an accurate and stable reading. 2. Suitable for freshwater culture, mariculture, swimming pool, beverage factory, wastewater treatment plant and laboratory. 3. Compact pen‑shape design, lightweight for mobility, you can test water anywhere to get the purest water. 4. High 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. 5. Adopts the digital screen display with backlight, which is more clear and convenient to read data. Specification: Condition: Brand New Item Type: Dissolved Oxygen Meter Material: Plastic Measuring Range: Dissolved Oxygen: 0.0- 20.0mg/L Temperature: 0～40°C Basic Error: Dissolved Oxygen: ±0.3mg/L Temperature: ±1°C Residual Current: ≤ 0.15mg/L Response Time: ≤30s (90% response at 20°C) Automatic Temperature Compensation Range: 0～40°C Power: 4 x LR44 Button Battery (not included) Package List: 1 x Dissolved Oxygen Meter 1 x Electrode3 x Replaceable Electrode Head1 x Instruction1 x Plastic Box Note: Please note that the product is shipped without electrode filler.