The Arnold is a air filter. A replacement for the Briggs & Stratton 272235 air filter that is used for the Briggs & Stratton 3-3.75 hp Classic/Sprint and 4 hp Quattro vertical shaft engines. These engines are from the Briggs & Stratton 92500 92900 93900 95900 96500 and 96900 series. This small engine foam filter prevents abrasive particulate matter like dust grains and others from entering the engine’s cylinders before those could cause mechanical wear and oil contamination.