Check the listing for details. MOX-4 Oxygen Sensor CITY O2 Sensor Oxygen Battery O2 Oxygen Sensor MOX-4 Oxygen. Condition: New. Listed at 108.61 USD. The MOX-4 Oxygen Sensor is a high quality CITY O2 sensor designed to accurately measure oxygen levels. This battery-powered sensor is suitable for use in a variety of industrial applications and is a reliable tool for testing and calibration purposes. With its durable construction and user-friendly design, the MOX-4 Oxygen Sensor is the perfect addition to any tester or calibrator kit. Its compact size and lightweight design make it easy to transport and use on the go, while its advanced technology ensures accurate and reliable readings every time. If you need a dependable oxygen sensor for your industrial needs, the MOX-4 is the perfect choice.