Newest in boat cover venting and support. Proper ventilation can prevent boat destroying fungi from attacking your boat's interior. The patented Boat Vent II installs quickly and easily, no screws or fasteners needed. The venting area allows for a 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 polycarbonate blend material for strength and UV resistance and will accommodate either 3/4" or 7/8" crutch tip support poles. Sold individually.