Preferably, the tubular body and {HEAD ~ the flange} of the flexible port have {TAIL ~ a circular cross section}, although other alternative configurations, such as ovoid, can be employed if desired 
have
Preferably , the tubular body and { HEAD ~ the flange } of the flexible port have { TAIL ~ a circular cross section } , although other alternative configurations , such as ovoid , can be employed if desired
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH