Allstar Aluminum Camshaft Thrust Button for Big Block Chevy Timing Cover features a camshaft thrust button. It fits the big block Chevy engines and is manufactured from quality aluminum material. The cam buttons limit lateral movement of the camshaft in engines without cam thrust plates. It can reduce friction for free horsepower. The machining of the cam sprocket may be required. It is backed by a 90-day limited factory and sold individually.