The FMDVKO4S is a direct replacement diverter valve unit by Forge Motorsport. They are milled from billet aluminum and use a piston based design that has proved successful throughout their entire range of application specific and universal valve products. Viton brand high temp silicone o-ring are used for sealing of the piston and the valve cap, Mobil 1 fully synthetic bearing grease for lubrication of the internals, and a proprietary spring rate is used to handle the widest possible range of boost pressures. The low-profile cap incorporates a knurled outer ring and a swiveling center section that allows for 360 rotation of the vacuum nipple for ease of fitment. This also allows for quick dis assembly of the valve without requiring removal from the vehicle should servicing of the internals be required. You'll see better throttle response and boost holding capabilities as well as increased reliability under higher boost loads. Sold as a pair of two valves. Easy installation.