Pier and Beam Vent Cover Options?

Hey all, we are looking to cover our pier and beam vents for the winter. We were told that we’d need the covers (bought some at ace hardware) and wing nuts, but as it turns out our vents have no place for a wing nut. We tried gorilla glue construction adhesive, but it is just not holding (probably since it’s cooler out). Has anyone had this situation and come up with an alternative solution? Thanks