Simply press the start/test button and the GasAlertClip Extreme is ready to use, providing dontinuous, reliable protection. This 3 year single gas detector requires no calibration, sensor replacement, battery replacement or battery charging. Compatible with the MicroDock II automatic test system, the simplicity of the GasAlertClip Extreme combind with minimal training requirements and negligible maintenance costs make the GasAlertClip Extreme one of the most cost-effective gas detection solutions for facility workers and onsite contractors.