{TAIL ~ A rolling cutter unit} for the rotary head of {HEAD ~ an earth boring system} that functions to form a passage through earth formations, comprising: 
{ TAIL ~ A rolling cutter unit } for the rotary head of { HEAD ~ an earth boring system } that functions to form a passage through earth formations , comprising :
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH