Engineered to provide cost-efficient gas detection, the Ultima XL/XT Series Gas Monitors are simply an outstanding choice. The units boast a hand-held HART port running over 4-20mA output provides convenient setup, calibration and diagnostics. The interchangeable smart sensors eliminate the need for reconfiguration, while local calibration employs LEDS and push-buttons. Indoors or outdoors, some of these explosion-proof models feature infrared technology that eliminates the need for frequent calibrations. Some units operations are based on dual-wavelength, heated-optics technology, which compensates for temperature, humidity and aging effects. The monitors use only one circuit board for increased reliability, and they're easy to install with two-piece field-wiring connectors.