This is the **NuVair O2 Quickstick (Oxygen Analyzer)** for Nitrox (Enriched Air). The main unit has been operating normally until now, but the sensor has reached the end of its life and is no longer working. Therefore, this is a **junk item (sold as-is) that requires sensor replacement**. The sensor is a replaceable electrochemical sensor specific to this model and can be purchased at online shops (new sensors are generally in the range of ¥15,000 to ¥20,000). I am listing this item because I will not be using Enriched Air (Nitrox) in the future and do not plan to purchase a new sensor. The photos show everything included. Please understand.