Manufactured from blue anodized 6061 aluminum. A direct upgrade replacement for the stock low cost plastic 29400183 front and 29400210 rear breathers inside the rocker cover. Where the stock umbrella valve can be problematic; the S&S O-ring design offers a superior seal; minimizes leaks and maximizes performance. The labyrinth design significantly reduces oil pass-through; keeping your engine running cleaner and smoother while burning less oil. - 6061 aluminum construction - S&S blue anodized finish - Dual O-Ring for a improved sealing - Labyrinth design to significantly reduce oil pass-through - Less oil burn - Improved durability when compared to stock plastic - Will not fit 23-up Gen2 M8 engines