Located behind {HEAD ~ front wall} 134 is a controller, 140, which controls the opening and {TAIL ~ closing} of the apertures of matrix 138 
Located behind { HEAD ~ front wall } 134 is a controller , 140 , which controls the opening and { TAIL ~ closing } of the apertures of matrix 138
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH