The B7 FLIGHT-Echo is perhaps the most useful flight bag ever designed. It's a fact that some days you need more gear than others. The B7E lets you carry a full set of flight gear for cross country and basic IFR flight. And then it lets you downsize to a smaller bag for those days when you're just going to take a quick VFR flight.
The B7E does NOT include a SLIM HANDLE KIT. If you ever think you'd like to remove the CS4 and zip just the two End Caps together to make the B0 SLIM, you'll need to make sure you also order an SLIM HANDLE KIT.
The B7 FLIGHT - ECHO is designed to hold one or two full-sized headsets plus a full suite of charts, and of course your iPad (or two), a large water bottle, plus all the small stuff you'll want along for the ride. It also serves as an unbeatable carry-on personal bag when traveling on commercial flights, or just as a terrific daily bag for a wide variety of personal and professional uses.
The CS4 and CS3 provide seven inches of storage depth (hence the name, "B7"), but keep in mind that there is also three thin flat storage areas BETWEEN the four modules for additional slim storage. (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 B7 (like zip a CS2 in between the CS3 and CS4) to add more storage on certain days. Any FLEX System module can zip onto any other FLEX System module. The Main Compartment of both the CS4 and the CS3 have locking zipper sliders.
The B7 FLIGHT will very commonly be used to carry two full-sized aviation headsets of any brand inside the CS4. (There is a nice, slightly-tricky way to 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. And then the CS3 will be used to hold a library of charts, or a iPad in it's bulky case, plus kneeboard, etc. A small collection of charts or flight docs can go in the spaces between the four modules. Surprisingly, a 13" Ultrabook or MacBook Pro can even fit into this "in between" space, and the iPad (or other tablet) can go in the main pocket on the FLAT CAP REAR.
The B7 FLIGHT 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 batteries, 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.
The other great thing about this bag is that it is actually FOUR bags for the price of one. Not only is it a B7 FLIGHT, but you can remove the CS3 and end up with the B4 SWIFT as a result. Or you can remove the CS4, leaving the CS3 between the end caps and have a nice compact personal bag (which could be called a "B3"). But you can also build a B0 SLIM by removing both center sections and zipping just the two End Caps together.