These 5 x 5 Grand National style hubs are machined from aircraft quality 7075-T6 aluminum. Hubs come with bearing races and 5/8-18" fine thread studs or optional 5/8-11" coarse thread studs. The hubs are designed to be used with a bolt-on rotor plate available to fit the most common rotor bolt patterns, or they may also be used with a rotor mounting hat. "WARNING: This product contains a chemical known to the State of California to cause cancer and birth defects or other reproductive harm."