Attwood's collector box is designed for intake or exhaust. Box mounts to the installation hole from the outside or inside of the hull. Box and vent are fastened to the hull as a complete unit. Ventilation hose (not included) twists into the bottom of the box to form a raised water barrier around its perimeter.
Installation hole size: 3-5/8" x 10-3/4"; depth: 5-9/16"