{HEAD ~ Each conduit} has {TAIL ~ a corresponding coupling mechanism} which enables it to move up and down 
{ HEAD ~ Each conduit } has { TAIL ~ a corresponding coupling mechanism } which enables it to move up and down
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH