The GasAlertClip Extreme is a single-gas detector that provides continuous monitoring for up to two or three years with no need for calibration, sensor replacement, battery replacement or charging. It is small, lightweight, and easy to use, simply requiring the user to press a button to start it. It can detect hydrogen sulfide, carbon monoxide, oxygen or sulfur dioxide. Accessories include carrying clips, straps, and a docking station for automated testing.