In {TAIL ~ use}, {HEAD ~ the block} may be made to form vertical or set back walls without pins or other securing mechanisms as a result of the high mass per front surface square foot 
In
In { TAIL ~ use } , { HEAD ~ the block } may be made to form vertical or set back walls without pins or other securing mechanisms as a result of the high mass per front surface square foot
REL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH