4" Day/Night Solar Vent - Stainless Steel Features:Circulates fresh air in boat cabin eliminating mold, mildew and musty air Moves 1,000 cubic feet of air/hour or 24,000 cubic feet of air/day (4" model) Rechargeable battery allows for 24-hour continuous operation Whisper quiet fan operation No wiring required Built-in on/off fan switch, LED lights and intake/exhaust switchHigh capacity NiMh battery operates vent for up to 24-hours without sunlight on a full charge Threads into included deck plate and can be removed from outside without tools Complete air and green water shut-off from below All Day/Night Plus models come complete with white plastic interior trim ring, insect screen, mounting hardware and an easy-to-understand installation manual Replaces NICRO 3" & 4" snap-in deck plates (fits existing holes once snap-in deck plates are removed)