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