This handy oil fill cap breather by Aeroflow Performance is the easiest wayto add an aftermarket catch tank to the GM LS engine without the need to modify theOEM valve cover. These late model valve cover fill caps screw into the valve cover like an ordinary cap. They feature an internal baffle inside the cap which helps to reduce transfer of to catch can. A -10 ORB is located in the centre for custom plumbingto the catch can or PCV. Billet aluminium construction with a black anodized finish.