The Briggs & Stratton 222698S is a genuine OEM flywheel key (also known as a Woodruff key). This small metal part is designed to lock the flywheel to the crankshaft, keeping the engine’s ignition timing perfectly aligned. Genuine OEM Replacement The Briggs & Stratton 222698S Flywheel Key is the factory-original part. It is specifically engineered to be a “sacrificial” component; if your mower blade hits a hard object like a rock or a thick root, this key is designed to shear (break). By breaking, it stops the engine instantly and protects much more expensive parts—like the crankshaft—from bending or snapping.