Built for the VFR Pilot who needs the essentials when flying: Headset, iPad, GPS, today's charts, kneeboard, radio, sunglasses, etc. And when you need, you have extra versatility because you can remove the CS4 and simply zip the two End Caps together to build the B-zero SLIM bag. Two bags for the price of one. And, of course, you can add space anytime you need by just zipping any FLEX System center section in between your current modules. The B4 outside dimension is 14" x 12" x 6". (Remember, it is a soft bag so it can expand slightly in every direction.) The interior storage of the main compartment measures 4 inches deep x 13.5 inches tall x 10 inches wide. The B4 SWIFT components are: POCKET CAP FRONT, CENTER SECTION 4, FLAT CAP REAR, SIDE POCKET ECHO (water bottle) and SIDE POCKET FOXTROT. Visit the BrightLine Bags website to see all the detailed information about all the components and features, as well as all the additional available modules and accessories.