The block 14 wherein said block protrusion comprises first and second oblong sections between which is positioned a joining section, said joining section having {TAIL ~ a narrower width} than {HEAD ~ either} of said first and second oblong sections 
The block 14 wherein said block protrusion comprises first and second oblong sections between which is positioned a joining section , said joining section having { TAIL ~ a narrower width } than { HEAD ~ either } of said first and second oblong sections
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH