This replacement oil seal is an authentic OEM part for a wide range of snow thrower engines. As its name suggests, this part seals oil into the engine. More specifically, though, this oil seal is used in the crankshaft and camshaft. These two parts are responsible for translating reciprocal motion, and as such, they experience a lot of jostling. To keep from rubbing and creating friction, they require a lot of oil. So that the oil does not leak, they are sealed with oil seals. After prolonged exposure to hot oil, oil seals will begin to degrade and lose their ability to tightly seal off a shaft. When this happens, oil will leak from the engine and those parts will begin to rub against each other. As more and more friction builds up, the engine will start to quickly overheat and burn oil. Since these seals are located deep inside the engine, be prepared to follow the owner's manual on how to access and reassemble the cam and crankshafts. This replacement oil seal is a high-quality part designed to match the specifications of Toro, Tecumseh, Lawn Boy, and Husqvarna appliances. It comes sourced from its original manufacturer and does not include and additional hardware.