The Case-it Sidekick Zipper Binder is an efficiently-designed organizer. Organize up to five subjects and store your pens, pencils, and other essentials in the convenient, removable file folder. This versatile organizer also features rigid body construction so that you never have to work about the binder buckling or warping. The D-901 uses Kraft board instead of PE board to give its binders a firm, stiff shape that won’t buckle or warp. The spine is specially designed so that your binder can lay flat when open, making it easier to add or take papers out, and to take notes in. For ease of mobility, use the built-in handle or shoulder strap that comes included with every Case-it Zipper Binder.