6061 Anodized aluminum rear wheel spacers for your drag bike. These are the industry standard in rear wheel spacers machined to the highest quality. The are already anodized bright black or clear anodize. If you provide us your dimensions, we will machine them to length for you at no cost. To fit the bearing on a big wheel application, outside diameter on drive side 30mm, outside diameter on brake side is 25mm. On small tire application drive side will more than likely be the 25mm bearing.