I don't use it for confined spaces, so 5000 ppm is plenty for me. If any building I am in is over 5000 ppm I need to leave immediately! https://www.burntec.co

I don't use it for confined spaces, so 5000 ppm is plenty for me. If any building I am in is over 5000 ppm I need to leave immediately! https://www.burntec.com/images/co220b.jpg https://www.burntec.com/images/co220b.jpg