Nicro Ventilations Day and Night Plus Solar-powered ventilation runs 24/7 to help fight mildew and keep your boat fresh. With their improved design, the Day/Night Plus Vents move air 600 cubic feet per hour, freshening your cabin while fighting mold, mildew and musty air. By running 24/7 on solar power during the day and charging on a small battery to run at night the constant flow of air produced by these vents helps to keep boat interiors dry which extending the life of upholstery, electronics and metal components. Vents easily retrofit to existing 3 3/4" Nicro vent cutouts. Direct-to-deck mounting affords greater security and protection against theft. Each vent includes an insect screen, below-decks shut off damper and internal on/off switch. Two blades (exhaust and intake) are provided with each vent. Install a pair of these to create efficient cross ventilation on your boat. Key Features Solar and battery-powered vents require little to no maintenance Stainless Steel cover No external power cords Rechargeable NiMH battery for up to 40 hours of continuous use without sunlight Waterproof exterior Two year limited warranty