means for attenuating high frequency electrical signals and for blocking {TAIL ~ the passage} of {HEAD ~ gas} through the passageway, said means including 
means for attenuating high frequency electrical signals and for blocking { TAIL ~ the passage } of { HEAD ~ gas } through the passageway , said means including
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH