One of the one way valves is located on the inside of one side of the barrier bag, and the other of the one way valves is located on the outside of {TAIL ~ the other side} of {HEAD ~ the barrier bag} 
One of the one way valves is located on the inside of one side of the barrier bag , and the other of the one way valves is located on the outside of { TAIL ~ the other side } of { HEAD ~ the barrier bag }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD