This 8mm diameter, circular cup shaped cutter is a fine grade, solid tungsten carbide. It is a replacement to fit the straight and the cranked Axminster Evolution Series Probes.
The edge of the cutter is sharp and ready to use. Being solid tungsten carbide, it will retain its sharp edge for a very long time, far longer than any HSS equivalent. The great advantage of the circular shape comes when the cutter eventually begins to lose its edge. Then you simply slacken the retaining screw and rotate the cutter slightly to give you a new sharp edge.
With a full 360° available, these cutters have a greatly extended working life.