Ventilation Clam Clamshell Vent Cover 215 × 180 × 70 mm White | 4BoatsCompact white clamshell cover designed to protect and control airflow through marine ventilation openings. Surface mounted for easy installation; measure your opening before fitting and use appropriate fasteners (screws not included). Design clamshell cover for airflow control and splash protection Dimensions 215 180 70 mm (8. 5 7. 1 2. 8 in) Colour white finish for low visual impact on deck Brand Ventilation Clam Use for marine ventilation openings;