{HEAD ~ A room air filter apparatus} includes a multi sided housing having longitudinally spaced first and second ends, a plurality of sides between the first and second ends, and {TAIL ~ a plenum} inside the housing 
includes
{ HEAD ~ A room air filter apparatus } includes a multi sided housing having longitudinally spaced first and second ends , a plurality of sides between the first and second ends , and { TAIL ~ a plenum } inside the housing
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH