The Parker House Grand Manor Palazzo Collection of Museum Bookcases can be used as a single bookcase (42 1/4-inch wide), double bookcase (75-inch wide), triple bookcase (105-inch wide) or any number of additional sizes due to it's modular design. Additional units add each 32 3/4-inch in width. Single bookcases come boxed complete. While bunched, the right pilaster is removed from the bookcase and re-attached to the right side of the last extension added. Extensions may be added to achieve any length of bookcase desired. Bookcases bolt together with 6 bolts, 2 in the crown, 2 near the middle and 2 inside the drawer box. The ladder rails can be removed and replaced with decorative bolts when desired.