This component is the knife guard for the cutterbar assembly on a grain harvester header. It mounts to the cutterbar ledger plate and provides the counter-edge against which the reciprocating knife sections shear the crop. The two mounting holes align with the ledger plate studs; the guard's inner profile guides the knife sections and maintains the correct shear gap. A worn or bent guard allows the knife to miss the counter-edge, resulting in ragged stubble and increased power draw. The manufacturer machines the guard to match the original ledger plate geometry so the shear clearance is maintained without shimming.