Inner pieces can be made in an infinite variety of ways to separate or cushion products, to strengthen the box or to prevent product movement by filling voids. This may be simple rectangles, or scored, slotted, scored and slotted, or die cut shapes. Many of the common interior forms have been given International Fiberboard Case Code numbers. The carrier classifications provide specifications for some pieces used in the packing of glassware and other fragile articles.
Pads are plain shapes of corrugated or solid fiberboard. They can be used to fill the space between the inner flaps of an RSC, to completely cover the bottom or top of a box, or to separate layers of product. Vertically, they can be used to separate products.
Tubes are scored rectangles, folded and sometimes joined with tape to form a multisided structure open at both ends. When used as sleeves for individual items such as glassware, adjacent shell provide double protection.