In {TAIL ~ accordance} with yet another preferred embodiment, the first central area has a diameter which varies between about 1.8 to 3.7 mm, and the second central area has a diameter which varies between about 1.4 to {HEAD ~ 2.9 mm} 
In { TAIL ~ accordance } with yet another preferred embodiment , the first central area has a diameter which varies between about 1.8 to 3.7 mm , and the second central area has a diameter which varies between about 1.4 to { HEAD ~ 2.9 mm }
OTH TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD