Feature: 1. High Accuracy and Sensitivity: The handheld O2 detector has a measurement range of 0‑30%Vol, with high accuracy and clear display. It also has time, date, temperature, and humidity displays to ensure that you breathe clean air. 2. Real Time Monitoring: Sampling at 1.5 seconds per time, the O2 tester equipped with alarm will alert you when the Vol value increases (supports turning off the alarm), and you can calibrate the tester to ensure accurate detection. 3. Rechargeable Battery: This detector has a built in 2000mAh large capacity battery, ensuring long endurance, no need for frequent battery replacement. Equipped with a micro USB charging interface, serving for 24 hours after charging for 2 hours. 4. Clear Display: The O2 detector is equipped with a high definition LCD screen, which is clear and easy to read, making it convenient to observe data at any time. Support screen brightness adjustment to care your eyes in different lighting conditions. 5. Applicable Scenes: This O2 tester is designed with a stable stand to meet your usage needs in various places, suitable for indoor sleep, travel, or outdoor activities, easy to store and carry, applied in for home, office, classroom, and other spaces. Specification: Item Type: Handheld O2 Detector Screen Display: High Definition LCD Screen O2 Detection Range: 0-30%Vol Temperature Detection Range: -10℃ to 50℃ Humidity Detection Range: 20%-85%RH Sampling Time: 1.5 seconds Battery: 1 x 2000mAh Rechargeable Lithium Battery (built in). Package List: 1 x O2 Detector 1 x User Manual 1 x Storage Box 1 x USB Cable