K&N Round Air Filter Assembly 5.25in ID / 5in Height / 5.125in Neck Flange / 1 1/4in Drop BaseK&N's custom air cleaner assemblies are designed with the racer in mind. They incorporate good looks as well as the superior air flow that you expect from K&N. These custom air cleaner assemblies are designed for use with any engine that uses a round element air cleaner housing. They incorporate our famous K&N Air Filters and provide more air flow than other assemblies of this type. Available in 4 different designs, the perfect assembly is sure to be