The lower surface and {HEAD ~ the upper surface} of {TAIL ~ the clasp} do not run parallel to one another 
The lower surface and { HEAD ~ the upper surface } of { TAIL ~ the clasp } do not run parallel to one another
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH