This flail is the impact element that strips grain from the straw as it passes through the threshing drum. It mounts on a bolt and nut assembly to the drum rotor; the flail’s curved face contacts the crop mat at high speed, separating the kernels from the straw. Flails are sold and installed in pairs, with the two pieces in each pair matched as closely as possible in weight. Each pair must be mounted on opposite sides of the drum to maintain rotational balance. After all flails are installed, the threshing drum must be balanced. When reconditioning the drum, replace the entire set of flails at once; mixing new and worn flails creates uneven mass distribution that leads to shaft runout. A worn or missing flail reduces threshing efficiency and accelerates wear on the drum bearings and counter-rotating components.