What is Carbon Monoxide?

This website is one of the best I've found:

http://www.carbonmonoxidekills.com/

Featured Product Safe T AlertTM Carbon Monoxide Detector alerts you to dangerous CO buildup and stores gas level in memory. Vibration resistant microprocessor technology designed especially for RVs offers reliable protection while moving or parked, with no false alarms. Carbon Monoxide Detector at Camping World