This K&N racing air filter has just two layers of cotton to provide even lower air restriction than our replacement air filter for street vehicles. Unlike K&N replacement air filters, fuel management modifications will be necessary with this racing filter. K&N racing air filters are washable and reusable and come with a one year limited warranty. This product is for closed course competition use only. This K&N racing air filter has just two layers of cotton to provide even lower air restriction than our replacement air filter for street vehicles.