These Polished and Chromed Hamburger's fabricated aluminum valve covers are for use on 1958-86 SB Chevy (283-400) engines. They are super strong, yet very lightweight. They are precision manufactured using 1/4" rails to provide a positive seal and eliminate oil leakage between the valve cover and head. This pair has one baffled breather hole per cover for use with breathers, caps or PCV valve (sold separately). They measure 3-1/4" tall and have a great looking Chromed and polished surface that is easy to maintain. This set includes mounting hardware, but gaskets are sold separately.