This flat washer is used to attach the idler pulley in a number of small and medium sized gasoline powered engines. These engines include snow blowers, log splitters, riding mowers, lawn tractors, and chippers. Because the idler pulley is subject to a great deal of resistance when the pulley is engaged, eventually the pulley will wear out. Should there be a squealing sound when engaging the drive, the problem is likely the idler pulley. In these cases, the pulley must be replaced. It is a good idea to replace the surrounding hardware when replacing the idler pulley; tNhis includes the flat washer, which is subject to corrosion during heavy use. To replace the idler pulley, first detach the spark plug cap. If on a mower or tractor, drop the mower deck. Remove the original pulley and install in order: replacement pulley, hex bolt, flat washer, flange nut. Apart from dropping the mower deck, the only tools required to complete this installation may be a 9/16 ratchet and combination wrench. This washer is a genuine OEM replacement part, designed to perfectly replicate the original piece. This washer is compatible with Troy-Bilt, Yard Man, Yard Machines, MTD, and Craftsman devices.