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