This is a replacement pre-filter for the self-contained, belt-mounted, battery operated Adflo Powered Air Purifying Respirator (PAPR) System.
It installs into the Adflo filter cover, between the spark arrestor (not shown) and the high efficiency particulate filter.
The high efficiency particulate filter may be, in turn, "stacked" on top of an OV/AG vapor cartridge for organic vapor/acid gas protection.
The Adflo PAPR provides respiratory protection for welders, as well as other applications where respiratory and face protection may be necessary.