AEM Tru-Time Adjustable Camshaft Gears increase horsepower and torque without having to change the camshaft(s) and are must-have items for engines that are milled, forced induction, high compression and/or utilizing aftermarket competition cams. AEM Tru-Time cam gears enable users to match cam timing with their vehicle's tuning state by advancing or retarding the cam profile(s) in one-degree increments via true laser-etched markings. Precision-cut gear teeth ensure no premature wearing of the cam gear's belt surface and AEM's anodizing on the adjustable cam gear's teeth is lab-test proven as the hardest anodizing process on the market. You have just purchased the BEST adjustable cam sprockets available. These AEM billet aluminum adjustable cam gears are CNC machined from billet aluminum and then laser etched with cam timing marks for adjustment up to ±10° at the cam or ±20° at the crankshaft. Using the vernier scale on the sprocket hub helps to do the cam timing changes quickly and accurately. The inner hub is anodized for lasting beauty and resistance to corrosion. The out gear sector is hard anodized for resistance to wear