The nontransparent hollow tube has inner and outer surfaces that define {TAIL ~ a wall} of {HEAD ~ the hollow tube} 
The nontransparent hollow tube has inner and outer surfaces that define { TAIL ~ a wall } of { HEAD ~ the hollow tube }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD