The present invention provides a cutter for an earth boring system that has a rotary unit which bores into {HEAD ~ earth formations} to form {TAIL ~ a hole} therein 
The present invention provides a cutter for an earth boring system that has a rotary unit which bores into { HEAD ~ earth formations } to form { TAIL ~ a hole } therein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH