The Porter-Cable 43215PC is a Combination Panel Pilot Router Bit. The Porter-Cable Professional Edge router bit is constructed of 4140 Alloy Steel, a harder grade of steel than standard cast steel bit bodies. The bit is annealed and heat treated to Rockwell hardness of 40-45 harder than is possible with cast steel bodies. The bit is precisely ground using computer controlled machining for precision tolerances and perfectly concentric shafts. The carbide tip is made from a specially blended micro grain carbide for superior results and longer lasting sharpness.