{TAIL ~ A sensor} is held in a substantially fixed position relative to the insulation in {HEAD ~ the cavity} 
{ TAIL ~ A sensor } is held in a substantially fixed position relative to the insulation in { HEAD ~ the cavity }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD