Replacement particulate prefilter for 3M Adflo Powered Air Purifying Respirator (PAPR).Replacement particulate prefilter for 3M Adflo Powered Air Purifying Respirator (PAPR). Installs into the Adflo turbo filter cover, between the spark arrestor and the High Efficiency particulate filter. For maximum safety and comfort, regularly check your equipment for worn or damaged parts.