Vibrant Performance blow off valve flange assemblies are made from your choice of 6061 aluminum or mild steel construction. Each kit includes an O-Ring for a leak free seal and also come with a radiused weld fitting that allows for a simple screw on of the matting flange allowing for a convenient option to switch to a difference BOV down the road if you choose. They are available for HKS BOVs, Greddy BOVs, Tial Style BOVs and Synapse Synchronic BOVs/DVs.