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