Don't let your interior suffer from mold and mildew damage. Proper ventilation can keep these boat destroying fungi from attacking your boat! Installs quickly and easily, with no screws or fasteners. The venting area provides for greater volume of exhaust air while closing the top to bottom gap - keeping water out! The Boat Vent II is manufactured from a superior grade poly carbonate blend material for strength and UV resistance and will accommodate either 3/4" or 7/8" support poles.