This Manual Air Vent was designed for numerous applications. Easy to install over foundation openings with vinyl siding. Remove cover to allow fresh air in your crawlspace. Ventilating your crawlspace helps control moisture that can lead to mold, fungus, damp rot and poor air quality. Replace cover during humid periods to keep humidity out crawl space or cover to keep cold out during winter to protect pipes. Also, if you decide to do an encapsulation you only need to put your cover on.