Dual outlet-type BOV. Dual Port vents both to the atmosphere and back into the air intake. Ports with sequential timing allow quieter operation during everyday driving while getting all the benefits of a vent-to-atmosphere BOV under race conditions. They are easily converted to a complete atmospheric or full bypass unit by using supplied port blanking plug. Catalog Installation Instructions Brochure - A general brochure describing a brand, company, product line. If brochure in question is for a specific product, use code PDB.