This catch tanks works by trapping oil fumes generated when running the engine, these are the hottest part of the oil circulating in your machine. As the oil evaporate the catch tank help to cool it and re-circulates the much cooler oil back into the engine. Lower oil a temperature means your engine can run more modifications as well as increasing a standard engines output due to the lowering of temperature. 

This oil catch tank/engine breather stops pressure building in your engine. It replaces the oil filler cap, and will fit engines with long and short dipstick. Comes with complete connections and fittings.