“EVO” ventilators achieve natural air circulation in the interior of your boat. They improve air quality, reduce humidity and eliminate carbon dioxide concentration indoors. Healthy atmosphere relaxes the crew and prolongs electrical devices life. “EVO” ventilators 70231 and 70235 are made of polypropylene and 70234 and 70238 are made of ABS. They come in rectangular and square shape and they can be combined with connector 70239 for better performance.