One rubber portion can be, for example, {HEAD ~ the central core} of {TAIL ~ the rubber thread}, while a second rubber portion can be a jacket surrounding the central core 
of
One rubber portion can be , for example , { HEAD ~ the central core } of { TAIL ~ the rubber thread } , while a second rubber portion can be a jacket surrounding the central core
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH