The system comes with two jigs. The 40* jig is for finer bladed kitchen knives and creates a 20* bevel on each side of the knife. The 50* jig is for heavier blades that will be subjected to heavy work. The 50* jig creates a 25* bevel on each side of the blade. A 40* bevel on each side of the blade would not be very conducive to a sharp useful edge.