These are great! They have models to fit Scott, Sperian, Draeger and MSA, and they do N-95 particulates, hydrogen cyanide, hydrogen chloride and acrolein, and convert carbon monoxide to carbon dioxide. 15-minute supply, and the website shows that oxygen and temperature are normally not issues. There's a very impressive PowerPoint presentation that can be downloaded as well. They are at http://www.lastchancefilter.com/ so check it out.