This is a CNC Machined flange that allows the HKS SSQV blow off valve to bolt right on to all 86-91 Mazda RX-7's Tricked out 2 piece designed has a 1" inlet to provide a perfect fit and leak-Free seal. Made of lightweight 6061 T6 billet aluminum. Slips into place using the stock hose & clamp. BOV not included.