These cutters were awarded a patent for their design. The stress of cutting is being borne by the body of the cutter, not the screw. These cutters also have the Her-Saf reverse helix design and screw-on feature. With the downward shear of the reverse helix design, these cutters perform just as well as our two flute cutter. These cutters are ideal for plunge cutting applications. The open design around the insert helps to cool the insert and the material being cut. The cooler the insert, the longer the edge stays sharp. With insert tooling, maintaining the overall diameter of the cut is elementary . When the cutting edge is dulled, rotate to a new sharp edge thus maintaining the exact diameter.