These main bearing caps are CNC machined from solid billet steel. The sides are blanchard ground to precise thickness. The bores are machined undersize and must be line bored after installation. The bearing cap nest is oversized so they can be machined to fit the block. They are available to fit the stock four bolt with straight holes or the 180 splayed side holes. Gold zinc plated. "WARNING: This product contains a chemical known to the State of California to cause cancer and birth defects or other reproductive harm."