The K&N E-4521 replacement air filter is constructed using an oil-free synthetic media. A tube of sealing grease is provided to help ensure an airtight seal. The E-4521 provides superior filtration, protecting your equipment's engine. This K&N air filter can be cleaned and used again. The E-4521 air filter fits some Kohler, Toro Multi Pro and John Deere equipment, in addition to other applications.