The Model A-222 CO monitor is produced for Marco Blastmaster in a weather resistant Pelican case that can be placed or hung at the job site and connected to AC or DC power supply. While continuously monitoring a compressed air sample connected to its sample inlet, the A-222 gives an alarm when CO in the sample exceeds a preset level (adjustable) or there is a discontinuity in the detector circuit. Compact and portable with sample flow regulator and a stable and superior electrochemical sensor, the A-222 is guaranteed to provide years of rugged service life under demanding industrial conditions.