The low coefficient of {HEAD ~ thermal expansion} ensures that the opening essentially does not change in size much due to temperature variations, while the high thermal conductivity provides for {TAIL ~ efficient heat transfer} 
The low coefficient of { HEAD ~ thermal expansion } ensures that the opening essentially does not change in size much due to temperature variations , while the high thermal conductivity provides for { TAIL ~ efficient heat transfer }
OTH OTH OTH OTH HEAD 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 OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL