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