This seal ring fits on the PTO shaft assembly of the host tractor. It sits between the shaft and the housing, preventing lubricant leakage and keeping contaminants out of the driveline coupling. A worn or hardened seal allows oil to weep from the PTO housing, which can lead to bearing damage from loss of lubrication. As an original-manufacturer component, the seal profile matches the groove depth and shaft shoulder geometry of the factory assembly, so no shimming or adapter is needed. On reinstallation, ensure the seal face is clean and press it square into the bore to avoid edge rolling.