Each sprocket half is precision machined, therefore the two halves mount up straight and flat to the hub. Early sprockets were sheared or punched causing the two halves to bend and not mount up flat. This would cause the chain to bind or be thrown off. The JRC precision-machined sprockets are labeled on each with the size making it easy for you to pair up your sprockets. The sprockets are also lightened, giving you less rotating weight. The halves are hard anodized to give wear resistance to the aluminum material.