They’re bimetallic bushes amde of iron sheets, with a low content of high-quality-carbon. They’re surface-tinned with lead alloy, bronze-coated and sinterized many times, at very high temperatures. Usually, the groove for the oil hole lubrification is made in the internal surface.
The MBM products are widely used in many car engines, transmission functions, vehicle frames, joints, balance shafts, steel-sheet springs, motorcycle clutches, polishing surfaces of gear pumps, car lifting, etc.