Downdraft pipe for Kitchen island

We need some infomation about the island that we have downdraft pipe that is under and it go through to outside wall.. WE need to know what kind of parts to cover the pipe which it is outside to keep from rain and ants come in.. If anyone or know someone that have kitchen island with downdraft vent n pipe, please give me all your information which we are build a house.. We already have the downdraft pipe under.. so need to know what to do with the pipe outside. We are going to buy the downdraft vent on the island..