Plastimos Low-Line Cowl/Dorade Box Combo provides continuous ventilation without water intrusion. Dorade boxes have a water-sensitive valve which opens and closes automatically to let air in and keep water out. Flexible PVC cowls are safer than steel, yet strong enough to withstand kicks, snags and wallops. Safer than rigid cowl ventilators, these flexible vents wont youre your line or jib sheet. Requires #8 fasteners –not included. Specifications Cutout Size: 3.6" Material: Dorade: rigid ABS plastic; Cowl: flexible PVC Included Equipment: Dorade, flexible cowl, storm cap, thru-deck sleeve with interior trim ring, on-deck sleeve with exterior trim ring Warranty: One year