Attwood Plastic Louvered Vents are made from rugged ABS plastic and will not rust or corrode, discolor or streak. No dangerous sharp edges to scratch or cut hands or feet. Designed for gunwale mounting to assure high vent mounting so that the boat will meet and pass the tip test. Features3-7/16" wide x 17-7/8" long x 7/8" high (1" neck).Installation hole size: 2-1/4" x 16-1/8".Predrilled with six mounting holes to accommodate #8 screws. Fits 1345 collector box.