... protection connector,high reliability and anti-interference ability optional 2 relay outputs: warn & switch control Range 0-400ppm within the ... panel,MMI functions Support for calibration, custom analog measuring range, relay action point set and so onLightweight, fashionable shell design, ... -1989 and related to air quality standards, the default value: relay action, 9ppm - # 1-6 PPM/OFF, 2 #, ON/OFF ...