Gas Alert Extreme Hydrogen Sulphide Compact and affordable, the Gas Alert Extreme reliably monitors for any single gas hazard within its wide range of available toxic gas models. With easy on/off operation, this single gas detector offers extended longevity with a field-replaceable battery and sensor. A wide range of tamperproof user options and multi-language display make the Gas Alert Extreme an ideal solution for a variety of applications; plus, datalogging is standard on all units. Calibration is a simple automatic procedure and is compatible with BWs Micro Dock II automatic test and calibration system.