Genuine OEM BMW Crankshaft Main Bearings Shell, part number 11218471812. These critical components support the crankshaft within the engine block and significantly reduce friction during operation. They are installed in sets around the crankshaft journals. The main bearings shells weigh 0.063 kg. Genuine OEM crankshaft main bearings are manufactured to precise tolerances to ensure proper oil clearance, minimize wear, and prevent catastrophic engine failure.