A transition or {TAIL ~ tapered portion} 50 extends from the portion 48 to {HEAD ~ an enlarged portion}, shown as a spherical cap 52 
A transition or { TAIL ~ tapered portion } 50 extends from the portion 48 to { HEAD ~ an enlarged portion } , shown as a spherical cap 52
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH