Spiral Cutter Head is designed with a true shear cut. It requires less horsepower, makes smaller chips, and less noise than other types of cutter heads. Unlike conventional single straight knives, you do not need to replace the knife if it becomes damaged or dull. Instead, if one knife edge is damaged or needs sharpening, simply turn it to another edge in seconds. You will only need to replace the inserts when four edges are dull giving you more life than speed steel knives. Your initial investment is paid back in no time.