As the name suggests this cutter is designed for undercutting mushroom shapes, but is also ideal for hollowing out small forms. The titanium nitride coating affords increased longevity of the cutter while at the same time relating ease of sharpness. Sharpening: Use a diamond file or honing stone around the profile of the cutter. To gain best results and increase the longevity of the cutter this simple procedure should be done little and often. Use the TurnMaster cutter holder to reshape the profile on the Robert Sorby ProEdge using a zirconium or ceramic belt or on a grinding wheel using a standard abrasive material. Sharpens to: 0.15 -0.2 microns Hardness of coating up to 85RC Material: TIN coating on M2 HSS. Related Products: These cutters are designed specifically for the TurnMaster.