{HEAD ~ The lower discharge surface} is spaced apart from the upper discharge surface by {TAIL ~ a distance} equal to D1 
{ HEAD ~ The lower discharge surface } is spaced apart from the upper discharge surface by { TAIL ~ a distance } equal to D1
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH