The SCM4 Carbon Monoxide Detector has an electrochemical sensor fast enough for walk-around tests.

• Field-replaceable CO sensor
• Advanced three-pin sensor measures 0 to 1000 ppm CO
• Calibrate to ambient quickly with ZERO button
• Audio and visual alarms (with MUTE function)
• Bright-blue backlit dual-display to test in dark crawl spaces
• Magnetic hanger for hands-free operation
• Alarm rate increases as carbon monoxide concentration increases
• MAX hold to help you zero in on the source
  Sensor Calibration: Factory calibrated 0 to 1000 ppm; 0 to 2000 ppm (less than 5 minute exposure time)
  Sensor Type: Electrochemical (specific to CO)
  Initial Accuracy:
  73°F±9°F, <75% R.H.
  0-15ppm ±5% reading ±1 ppm after zeroing
  16-35ppm ±5% reading ±2 ppm after zeroing
  36-1000ppm ±5% reading ±5ppm after zeroing
  15 to 90% R.H., non-condensing
  Storage Environment: 32 to 68°F (0 to 20°C) at
  <80% R.H. with battery removed from meter.
  Battery: 9V.
  Battery Life: 150 hours typical alkaline.
  Auto Power Off: After 15 minutes.