A-B1697124-AI REED-BREATHEROne New Aftermarket Replacement Reed Breather Fits Briggs and Stratton Small Engines This aftermarket replacement reed breather (also called a breather reed or reed valve) Fits Briggs and Stratton (B&S) small engines used in lawn mowers, lawn tractors, and other outdoor power equipment. The reed breather is part of the engine crankcase ventilation system it regulates crankcase pressure by allowing gases to escape while preventing oil and contaminants