We make strong bottom boards, from 3/4" pine NOT plywood like others do. Screen Bottom Boards provide better ventilation which is necessary in a hive and many use them to help control mites, as mites will fall out of the hive through the screen. Bees cannot fly through the screen which is important to prevent robbing from other hives. Fully assembled and painted.Comes with long entrance cleat. Screen can be left open all year but if desired, you can cut a piece of cardboard to cover screen in winter.