Dual outlet-type BOV. The Kompact Dual Port vents into the atmosphere and back into the air intake. Ports with sequential timing allow quieter operation during everyday driving while still offering the performance and sound of a vent-to-atmosphere BOV when the going gets more challenging.Dual Port vents both to the atmosphere & back into the air intake. Ports with sequential timing allow quieter operation during normal driving, while getting all the benefits of a vent-to-atmosphere BOV under race conditions.