These Officially Licensed Chevrolet Valve Covers valve covers are made of heavy-gauge steel for small block V8s. In most cases, these covers are at least 20% thicker than typical aftermarket covers. This prevents leakage around the valve cover flange area, typically caused by over-torqued fasteners. The valve covers bear the Chevrolet and Bow Tie logos. Oil-restricting baffles are offered in some covers for those who want to maintain the PCV hookup.