This creates {HEAD ~ a generally flat surface} on the top of the dome with {TAIL ~ the dome} like sides sloping away from, and generally not engaging, the diaphragm 
This creates { HEAD ~ a generally flat surface } on the top of the dome with { TAIL ~ the dome } like sides sloping away from , and generally not engaging , the diaphragm
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH