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: None - dummy sensor (OU) outflow Sensor 4: None - dummy sensor (IN) Housing: Yellow housing Region: China Mining Approval