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