A-B1270579S-AI FILTER-A/C FOAMOne New Aftermarket Replacement Foam Air Cleaner Filter Fits Briggs and Stratton (B&S) Small Engines This foam air cleaner filter (A C foam element) keeps dirt, dust, and debris out of the carburetor and combustion chamber on select Fits Briggs and Stratton 3 HP and 3. 5 HP vertical shaft small engines used in lawn mowers and outdoor power equipment. Regular replacement of the foam filter element maintains proper airflow and protects engine internals