In the preferred embodiment of FIG 10, {HEAD ~ diameter D3} is less than both diameters D1 and {TAIL ~ D2} 
is less than
In the preferred embodiment of FIG 10 , { HEAD ~ diameter D3 } is less than both diameters D1 and { TAIL ~ D2 }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL