A breather is a component found in the engine that allows for the release of pressure and the circulation of air. This part specifically refers to a breather designed for use in Cummins engines. As an engine operates, it generates heat and pressure which can build up inside the crankcase. Without proper ventilation, this pressure can cause damage to various engine components or even result in oil leaks. The breather serves as a vent that allows fresh air to enter the crankcase while also allowing any excess pressure or gases to escape. This helps maintain optimal engine performance and prevents damage from occurring due to excessive heat or pressure buildup within the engine.