Each of the first and second end surfaces includes an upper portion connected to a respective one of the first and second cutting edges, and a lower portion connected to {HEAD ~ the upper portion} by {TAIL ~ a concave transition portion}, wherein the lower portion is recessed axially inwardly relative to the upper portion 
Each of the first and second end surfaces includes an upper portion connected to a respective one of the first and second cutting edges , and a lower portion connected to { HEAD ~ the upper portion } by { TAIL ~ a concave transition portion } , wherein the lower portion is recessed axially inwardly relative to the upper portion
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