The pressure supply conduit communicates with an external source of air, or {HEAD ~ a detachable cartridge} of {TAIL ~ a biologically compatible compressed gas} 
The pressure supply conduit communicates with an external source of air , or { HEAD ~ a detachable cartridge } of { TAIL ~ a biologically compatible compressed gas }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL