Complete set of chipper knives and fasteners from WoodlandPRO. Chipper knife kits include all the knives, nuts & bolts needed to change out your brush chipper disc or drum. WoodlandPRO chipper knives are made of A8 Modified steel, and each knife goes through a dual heat treat process, ensuring a very hard cutting edge with a tough, less brittle center. All fastener hardware is made of Grade 8 steel.