{HEAD ~ The bottom surface} of {TAIL ~ the mounting surface structure} attached to a top end of the adjustable post mechanism 
of
{ HEAD ~ The bottom surface } of { TAIL ~ the mounting surface structure } attached to a top end of the adjustable post mechanism
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH