said main portion and tubular portion having {HEAD ~ an inner surface} and {TAIL ~ a generally arcuate shaped outer surface} 
said main portion and tubular portion having { HEAD ~ an inner surface } and { TAIL ~ a generally arcuate shaped outer surface }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL