GX4 Gas Monitor includes simple on-site calibration check, self-updating calibration certificate, 2 year data logging, WiFi connectivity, and auxiliary plug-in audible and visual alarms. This unit can be wall-mounted, mounted to a Radex Airline Filters (part 10NV04900), or a custom heavy duty carry case. Does not include sensors. Add part 10NV0842001 for Carbon Monoxide sensor, 10NV0842003 for Hydrogen Sulfide sensor, or 10NV0842004 for Oxygen sensor.