The B4 SWIFT come with two side pockets: The Side Pocket Echo, which is a totally unique insulated adjustable water bottle pocket, and a Side Pocket Foxtrot, which is our large fully zipper-enclosed pocket that can hold almost anything, including a large "brick" handheld radio.
The CS4 provides, that's right, four inches of storage depth, but keep in mind that there is also two thin flat storage areas BETWEEN the three modules. (Remember, it is a soft bag so it can expand slightly in every direction.) Keep in mind also that you can add any other Center Section to the B4 (like zip a CS2 in between the CS4 and the FCR) to add more storage on certain days. Any FLEX System module can zip onto any other FLEX System module.
The Main Compartment of the CS4 has locking zipper sliders.
This configuration will very commonly be used to carry two full-sized aviation headsets of any brand. (There is a nice, slightly-tricky way place two large headsets - like the BOSE A20 - inside this space. Just "intertwine" the ear cups in opposite directions. It's really nice to fit two headsets of any kind in such a relatively small space.)
There is a specially-designed pocket on top of the CS4 to hold Sunglasses and their case.
A small collection of charts or flight docs can go in the space between the CS4 and either of the End Caps. A 13" Ultrabook or MacBook Pro can also fit into this "in between" space, and the iPad (or other tablet) can go in the main pocket on the Flat Cap Rear.
The B4 SWIFT also works amazingly well as a daily personal bag and/or as a commercial carry-on bag. A 13" laptop plus a load of documentation plus an iPad, plus all the small stuff like cables, adapters and support stuff for all your technology, your digital camera, snacks, etc - all of this fits easily in this bag. Even your noise-reduction headset for those long flights.