CY-12X Oxygen Analyzer with manual calibration function and a convenient carrying case. Purchased around August 2025. Used for approximately 40 days from early October to mid-December. Used for about 30 seconds per use, 10 times a day. Sealed from the outside air with the blue cap when not in use. When measuring the oxygen of a device that has been running for 954 hours, the reading was 78.9% when calibrated to 21% in the atmosphere, indicating normal functionality. The connector part of the sensor cable had a slight looseness from the beginning, so it has been reinforced with insulating fusion tape as a precaution. All original accessories are included. I understand that those who need this likely need it urgently, so I will ship it within 24 hours. Thank you for looking.