Large display continually monitors primary IAQ (Indoor Air Quality) parameters: Air Temperature, RH, CO2. Poor air quality may cause tiredness, inability to concentrate, and even illness (i.e., Sick Building Syndrome). This instrument is ideal for monitoring indoor air quality in crowded public spaces with potentially high levels of CO2 (carbon dioxide) such as offices, factories, classrooms, hospitals and hotels. Recalls min/max CO2 levels and provides visual alarms for maximum CO2 threshold. Automatic Baseline Calibration (ABC) and maintenance free NDIR (non-dispersive infrared) CO2 sensor ensure long-term accuracy, stability and reliability. Comes with an AC adaptor and will stand on a desk-top or wall mount. Dimensions: 4½" × 4¼" × 1" (108 × 115 × 25 mm) Weight: 6 oz (170 g).