Each end surface includes an upper portion connected to the cutting edge, and {HEAD ~ a lower portion} connected to the upper portion by {TAIL ~ a concave transition portion} 
connected by
Each end surface includes an upper portion connected to the cutting edge , and { HEAD ~ a lower portion } connected to the upper portion by { TAIL ~ a concave transition portion }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL