The Computer Portfolio was designed to fit into the lid the larger PC II case and behind the elastic strap to allow you to protect and carry a notebook computer or other item. This accessory is best used with cases that have an elastic cross over strap in the lid as is found in the PC II Standard case. The black strip on the bottom of this portfolio is Velcro hook that will attach the portfolio near the hinges in the lid. There is a lightly padded rectangle compartment with a security flap and Velcro strip that is designed to face towards the lid. To secure this assembly in place, please use the elastic cross over strap.