In a preferred embodiment, the passageways are {HEAD ~ holes} having {TAIL ~ substantially equal dimensions} 
having
In a preferred embodiment , the passageways are { HEAD ~ holes } having { TAIL ~ substantially equal dimensions }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL