{HEAD ~ a housing} having a passage sized to receive {TAIL ~ a catheter} having an outer wall 
{ HEAD ~ a housing } having a passage sized to receive { TAIL ~ a catheter } having an outer wall
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH