Weld On Flange Kit for HKS SSQ BOV (Mild Steel Weld Fitting / Aluminum Flange) Material Mild Steel Weld Fitting / T6061 Aluminum Flange Warranty 30 Day Limited Warranty Notes Vibrant Performance makes it easy to weld Blow Off Valve mating flanges to your induction plumbing.Each BOV Flange Kit comes complete with a radiused weld-on fitting that is threaded so that you can screw on the mating flange.The Weld Fitting is made of Mild Steel and the Flange is made of T6061 Billet Aluminum. Each kit includes an O-Ring for a leak free seal.