This cap is included in all Hagan fuel door
It is made to screw into late model large thread filler spouts. You never
have to remove the cap to re-fuel, just push the pump nozzle through the center
valve. Vented for vacuum and can be modified to vent for pressure.
California users or others using Vapor Recovery fueling systems: Please refer to McCuff Sport at McCuff.com to prevent damage to the cap.