A420 WPL6 mloog reducer yog ib hom reducer, uas yog nyob rau hauv cov duab ntawm concentric cov qauv sib dhos. Nws muaj ob qhov xaus, ib qho kawg muaj qhov kawg ntawm txoj kab uas muaj qhov loj dua, thiab lub hauv paus me me yog cov sib xws, uas yog, concialric.