Diesel particulate filter
A diesel particulate filter (DPF) is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. == Mode of action == Wall-flow diesel particulate filters usually remove 85% or more of the soot, and under certain conditions can attain soot removal efficiencies approaching 100%.
Source: Wikipedia — Diesel particulate filter (CC BY-SA 4.0)