Fully recirculating valve. A quiet alternative to the atmospheric BOV, the Plumb Back systems vents all excess pressure back into the intake system. . APPLICATION: Ideal for cars with sensitive Air-Flow systems and off-road applications as the fully-sealed design of the Plumb Back prevents any foreign matter entering the system. SUPPLIED WITH: Quick-Release V-Band Clamp, 38mm weld-on adapter, Instruction CD and Sticker.