Irregular shapes may also be chosen so as to accommodate {HEAD ~ features}, such as external fittings or {TAIL ~ fluid control devices} 
such as
Irregular shapes may also be chosen so as to accommodate { HEAD ~ features } , such as external fittings or { TAIL ~ fluid control devices }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL