{HEAD ~ Each} of the components, including the mirrors, anode, and cathode, must be sealed to the block to form {TAIL ~ a gas tight seal} 
{ HEAD ~ Each } of the components , including the mirrors , anode , and cathode , must be sealed to the block to form { TAIL ~ a gas tight seal }
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL