Brake Hydro Boost Push Rod Baffle & Retainer with plastic insert. These retainer gets damage when removing to repair leaks. This listing is for two different size retainer, Earlier model hydro boost unit use smaller retainer and around 2003 year and up. Later model hydro boost use large retainer. Message us if you have any questions or need any help with this product. We also sell seal kits for Brake Hydro boost units. Note: All manufacturer's names, part numbers, and symbols are registered trademarks of these manufactures and supplied for reference purposes only. PB Sales, Inc. is in no way implying that any part listed is the product of these manufacturer's or that we are affiliated with any of these manufacturer's .