at least first and second openings configured to allow {TAIL ~ fluids} to flow into the first opening and out of {HEAD ~ the second opening} 
at least first and second openings configured to allow { TAIL ~ fluids } to flow into the first opening and out of { HEAD ~ the second opening }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD