{TAIL ~ The spacer} means is in operative contact with the light transmitting cover and is located between the first envelope and {HEAD ~ the cover} 
{ TAIL ~ The spacer } means is in operative contact with the light transmitting cover and is located between the first envelope and { HEAD ~ the cover }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD