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