This screw-and-nut set secures the knife sections to the cutterbar of a grain-harvester header. It passes through the knife section and the cutterbar, with the nut on the underside, clamping the assembly against the hold-down clips. A worn or missing fastener allows the knife section to loosen, which causes uneven cutting and accelerated wear on the ledger plates. The set includes both the screw and the nut, matching the original thread and length so the clamping force is restored without shimming. On reinstallation, tighten the nut to the specified torque to prevent loosening during operation.