{HEAD ~ The particulate matter reducing apparatus} 1, wherein {TAIL ~ each} of 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 
wherein
{ HEAD ~ The particulate matter reducing apparatus } 1 , wherein { TAIL ~ each } of 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
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