The particulate matter reducing apparatus 1, wherein {HEAD ~ each} of {TAIL ~ the filters} has a central through hole of a diameter approximately the same as or greater than that of the exhaust pipe and smaller than half the outer diameter of the filter 
of
The particulate matter reducing apparatus 1 , wherein { HEAD ~ each } of { TAIL ~ the filters } has a central through hole of a diameter approximately the same as or greater than that of the exhaust pipe and smaller than half the outer diameter of the filter
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH