The CS5 was developed primarily for our IFR Flight Customers. By adding a CS5 to any configuration, you can now add IFR Binders and documents, without having to repack. In addition to IFR equipment, the CS5 is perfect for a couple days’ worth or clothes, two more sets of headsets, or a 13" laptop. The CS5 makes a great bag all by itself. By adding end caps you now have an amazing carrying case. On the CS5 there is top level access. Simply unzip the top zipper, which is also a sunglasses holder, and reach down and grab your items. This item does not include a Main Handle or Shoulder Strap. If building a custom bag, make sure your order includes one or both. The CS5 also comes with a divider shelf that is attached to the sidewalls of the compartment by use of Velcro on each end. The velcro panels on the bag walls are quite large which allows you to move the divider shelf up and down to position the shelf right where you need it for your stuff (or take it completely out if you need). If you have the divider shelf installed, and if you're accessing the bag only from the top access, you won't get the items underneath the divider shelf. You can also zip open the entire front panel of the module, thereby allowing you to grab all the items inside, both above and below the divider shelf. So the CS5 has both top access AND side access. NOTE: THE CS5 OPENS TO THE FRONT. Until Aug 2017, the CS5 used to open to the Rear. We changed this for practical purposes. Every module in the FLEX System has a front surface and a rear surface. All of the modules are one-directional by necessity. Both the CS4 and the CS5 open to the front. This means that if you plan on building a bag based primarily on the CS5, you should know that the PCF (Pocket Cap Front) will attach to the front opening side, and the FCR (Flat Cap Rear) will attach to the rear panel of the CS5 which is the non-opening panel.