Commercial Grade reversible bottom board has the traditional 3/4" entrance height on one side and 1/2" on the other. Made with tongue and groove cross pieces to help keep moisture out. Includes wooden entrance reducer for winter use or with a new hive. Made with Eastern White Pine our commercial grade Bottom Board may have small solid red knots but otherwise clear wood. All wood is strong and solid and will give years of service. Choose from unassembled or assembled. 10 Frame dimensions -22" long x 16 1/4" wide x 2” tall 8 Frame dimensions -22" long x 13 3/4" wide x 2” high