Proflow's oil fill cap breather is the easiest way to add an aftermarket catch tank to the GM LS engine without the need to modify the OEM valve cover. These late model valve cover caps screw into the valve cover like an ordinary cap. They feature an internal baffle inside the cap which helps to reduce transfer of oil to the catch can. A -10AN ORB is located in the centre for custom plumbing to the catch can or PCV. Billet aluminium construction with a black anodized finish. Also comes with a replacement o-ring.