The Pocket Cap Rear attaches to the CS2, CS3, CS4, CS5, and CS11. There are nine pockets on the outer surface of the Pocket Cap Rear. You can plainly see three different pocket locations. Each of these three pockets pocket compartments actually contain three pockets: [1] A main pocket area. This Main pocket area is designed to hold your mobile device, wallet and keys. [2] A small secondary pocket tucked in the top of each pocket. This pocket is designed to hold a flashlight and fuel tester. [3] And then a small flat pocket on the front cover of each pocket. These pockets are great for organizing all the little stuff in your personal and professional life. The Pocket Cap Rear is not designed to be used alone because the separation zipper would be exposed and could be damaged. This item does not include a Main Handle or Shoulder Strap. If building a custom bag, make sure your order includes one or both. NOTE: The FLEX modules WILL NOT WORK with (will not zip onto) any older BrightLine Bag. The zippers had to be of a different type to allow this modularity concept to work. The Pocket Cap Rear can attach to all of the back panels of the FLEX System modules NOTE ALSO: The Pocket Cap Rear is one-directional (as are ALL of the FLEX System modules). It is always rear-facing.