The Torqeedo Ventilation Adapter replaces the cover of the membranes. It's to be used in cabins and in closed compartments. When installing the battery in a battery room with a ventilation system provided or in a well-ventilated room, the ventilation adapter is not needed. Not needed in a battery room with a ventilation system or in a well-ventilated room | Torqeedo Venting Adapter Power 48-5000