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