This can be an oxygen tank or {HEAD ~ a unit} that will treat {TAIL ~ the air} and make it more beneficial 
This can be an oxygen tank or { HEAD ~ a unit } that will treat { TAIL ~ the air } and make it more beneficial
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH