VS Series Units by CellarPro. Self contained and fully charged. These cooling units fit in a hole in the wall and can vent into an adjoining room or outdoors. The VSi (indoor) units vent indoors. The VSx (Exterior) units are meant to vent outdoors. Performance testing shows that this unit maintains optimal cellar temperature and humidity conditions in extreme conditions up to 110F more effectively than similar units from competing brands. VS units also are significantly quieter than comparable units from other brands.