Filter cover only. Filter cover holds spark arrestor, prefilter and high efficiency particulate filter and is for use with 3M Adflo Powered Air Purifying Respirator (PAPR). HE particulate filter, prefilter and spark arrestor sold separately.Help maximise the service life of your 3Mfilters with 3M PAPR Filter Covers. These fitler seal covers help to maintain the condition of your filter by sealing it whilst in storage or not in use, keeping it from untintenttionally capturing debris or contaminants. A filter cover should not be used while wearing the turbo unit or respirator. Always remove cover before using filter.