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