The ORIGINAL SHEar & heLIX spiral cutter non-grind design! Made in the USA by Byrd Tool Corp., these indexable carbide insert cutterheads give a shear, staggered cut instetad of a single, straight knife cut. Not only does this provide a superior finish on your work-piece, it is a lot easier on your dust collection system because the staggered spiral configuration of the inserts allows for the break-up of the chips. Another benefit to the indexed insert design is ease of maintenance. Dull or damaged insert knives are individually replaced, a much more cost-effective option than having to replace expensive knive blades the full length of your planer or jointer head. Each cutterhead comes with 5 extra inserts and a torque driver to aid insert replacement. This cutterhead is for use on the Delta DJ-20 8-in. jointer.