Fidanza Adjustable Cam Gears are made from the very highest quality 6061 T6 aluminum. They are CNC machined to more exacting tolerances than even original gears. The outside ring is coal blasted before being hard anodized. The coal blasting gives the gear a textured surface for the belt to hold on to. The hard anodizing makes the outer ring incredibly durable. The inner ring is designed for strength, function and good looks. Fidanza uses a very innovative system to fasten the two gears together. Stainless Steel studs are put through the back of the outer gear and then sealed in place with Loctite. The inner gear is then fastened with stainless steel nuts and lock washers. This gives the user the ability to increase the amount of torque used to tighten the fasteners with no risk of stretching to the aluminum threads. For durability and function - you can't beat a Fidanza cam gear!