said third plane of said lower surface of said clasp lower part being parallel to {HEAD ~ said second plane} of {TAIL ~ said edges} of said open underside of said clasp upper part ; and 
of
said third plane of said lower surface of said clasp lower part being parallel to { HEAD ~ said second plane } of { TAIL ~ said edges } of said open underside of said clasp upper part ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH