Two sides to display and two sides for storage in one unit. The eight display shelves are fixed, while six of the book shelves are adjustable. Caster mounted. The height and width of the opening of the open shelves is 10ยผ"H (from the bottom-side of one shelf to the top-side of the next shelf down) X 21ยพ"W. Each of the display shelves openings at the ends of the unit is 10-3/16โ Tall, 11-11/16โ Wide, 2-1/2โ Deep with a 2โ lip on the front. The adjustable shelves are 18.25โ long x 11โ deep. If they are evenly spaced on each side, there is 10โ between each shelf. The sides are 21โ long x 2.25โ deep and 10โ between each shelf.