The foam Briggs & Stratton 5099 lawn mower air filter provides protection against dirt and debris that can clog your engine. Used on select 300-500 series engines this original equipment replacement part ensures top performance. Replacing your air filter yearly will provide a lasting life for your mower’s engine. This filter was designed to manufacturer standards and tested to help deliver optimum performance of your Briggs & Stratton engine. To ensure a proper fit please reference your owner’s manual.