The apparatus 11, wherein said gas delivery system comprises {HEAD ~ a face mask} coupled to {TAIL ~ a flexible conduit} 
The apparatus 11 , wherein said gas delivery system comprises { HEAD ~ a face mask } coupled to { TAIL ~ a flexible conduit }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL