{HEAD ~ means} for discharging the carbon dioxide from the canister and into {TAIL ~ the housing} 
{ HEAD ~ means } for discharging the carbon dioxide from the canister and into { TAIL ~ the housing }
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL