Set of two 6304 bearings for the Active crankshaft (manufacturer TATA). The bearings hold the crankshaft in the crankcase and let it rotate under high load.
Replace them if the engine hums, vibrates, the crankshaft has play, or before an engine overhaul. When replacing, change both bearings and the crankshaft oil seals, otherwise air may leak in. When buying, compare the markings on the old bearing: they define the size unambiguously.
