The GasAlertClip Extreme reliably monitors for oxygen. This single-gas detector requires no calibration sensor replacement battery replacement or battery charging. The simplicity of this monitor combined with minimal training requirements and low maintenance costs make it one of the most cost-effective PPE solutions for facility workers and on-site contractors. Water-resistant unit provides two years of continuous maintenance-free protection. Record keeping is accurate and easy with automatic event logging. Unit features a full function self-test of sensor battery status circuit integrity and audible/visual alarm.