Whether you’re protecting general workers or responders in industries includingpetrochemical, steel, or utilities, the Honeywell BW™ Flex Series delivers what youneed in an easy to use serviceable package. Sensor 1: %LEL (combustibles), catalytic, filtered Sensor 2: O2 (Oxygen) Sensor 3: NO2 (nitrogen dioxide) outflow Sensor 4: CO-H (H2 resistant CO) inflow Housing: Black housing Region: MED/ATEX with Performance (LEL/O2)