Forged Billet Aluminum Vented Rotor Offset Hubs are made from premium grade alloy billets are forged into shape under high heat and pressure, then CNC machined for precise fit on each spindle application. Intended for use with intermediate adapter plates, but can also be used with aluminum mounting hats for custom applications. These specific 40-51 Oldsmobile Hubs are single drilled to a 5 x 5.00" wheel lug pattern. These Hubs include bearing races and use an included press-on steel cap (Part # 270-12403).