Sierra Monitor Model 5100-04-IT Carbon Monoxide Gas Sensor Module utilizes smart sensor technology. This network-enabled gas detector includes: Extended calibration frequencies only requiring calibration every six months; non-intrusive, one-person calibration; SIL-2 certified for long-term reliability; and more.Sierra Monitor Corp. , www.sierramonitor.com, (800) 727- 4377.Circle 322