This cap is included in all Hagan fuel door
kits.
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.