Fitment and Product Information. Crafted from 6061-T6 aluminum alloy, these valve covers have successfully endured rigorous testing, providing that they are built to last. The incredible ability to withstand the harsh elements of racing makes these the perfect solution for the street rod and racing applications. Thicker fabricated billet rails and better materials assure long lasting durability, individually pressure-tested. Offered in silver, clear, black finishes. WARNING : This product can expose you to chemicals including Styrene, which is known to the State of California to cause cancer.