The support 2 wherein {HEAD ~ the envelope} of one support can be stacked on {TAIL ~ the envelope} of another support and used in multiple 
stacked on
The support 2 wherein { HEAD ~ the envelope } of one support can be stacked on { TAIL ~ the envelope } of another support and used in multiple
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH