S&S die-cast rocker covers for 1984-'99 Harley-Davidson big twin engines are made using the more economical die casting process. All S&S rocker covers include formed Viton o-rings for leak-free operation; our proven two-piece design makes for a simple installation. Cast rocker boxes use an exclusive one way valve which is built into the rocker cover gasket to control oil carry over in "head breathing" engines Kit includes two covers and all necessary gaskets, o-rings and mounting hardware. S&S Part #: 90-4095