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: None (dummy sensor) Sensor 3: SO2 (sulfur dioxide) inflow Sensor 4: None - dummy sensor (BI) Housing: Yellow housing Region: Japan