Use the Titan Controls Atlas 6 indoor air quality (IAQ) monitor on a table top or mounted to a wall. This unit measures CO2 ppm levels, air temperature and humidity. 

The Titan Controls Atlas 6 accurately monitors your indoor grow area or greenhouse. You can even connect the meter to your PC using an RS232 interface.

The Atlas 6 gives you good reference points so you can really dial in your growing conditions. It helps you evaluate where problems may exist with your environmental controls so you can determine how to perfect them.

This monitor utilizes a stable NDIR sensor for CO2 detection. Utilize the ABC(Automatic Baseline Calibration) or do a manual CO2 calibration. It provides both visible and audible 80db CO2 alarm features for safety.

The Altas 6 also incorporates an alarm output for ventilation control! The screen simultaneously displays CO2 ppm level, temperature and humidity readings.

Specifications:

CO2 Range: 0 Parts Per Million (PPM) to 9,999 PPM
Temperature Range: 14°F to 140°F (-10°C to 60°C)
Humidity Range: 0.1% to 99.0%
Statistics of weighted averages: TWA - 8 hours weighted average, STEL - 15 minutes weighted average

Comes complete with 120 Volt power adapter and operations manual. Carries a 2-year warranty.

More info (PDF format)