K&N Steel Base Crankcase Vent Filters have a one piece design with a rubber or chrome top and a vent tube added to the base. Filters can be pressed into rubber grommets in valve covers for direct mounting. All base plates are chrome plated. Tubes are made of zinc. Note: Legal in California only for racing vehicles which may never be used, registered, or licensed for use upon a highway. See knfilters.com for CARB status on each part for a specific vehicle.