It has only cover function

Camber shims are used for adjustment

https://ozparts

focusing on reducing back pressure and featuring high-performance turbines

BOV Kompact Dual Port-20mm Xtremeclutch It has only cover functionDual outlet type BOV. Dual Port vents both to the atmosphere and 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. Easily converted to a full atmospheric or full bypass unit by using supplied port blanking plug. APPLICATION: Fits most cars using the factory BOSCH or DENSO bypass valves. Supplied With: Port Blanking