The B16 Contain is the B10 Classic with 5� Center Section zipped in between the front and rear bag of the B10. The B16 is designed for people who need a little more storage than the B10 will offer. It was designed primarily for IFR pilots who need the extra room for Charts and IFR Binders. The 5� Center Section affords the heavy IFR pilots the room they need. And, with the FLEX System, one can simply unzip the 5� Center Section and remove it when not in use. The idea being that why carry more bag than you need? Zip it in when you do need it. Zip it out when you don�t. The B16 Contain comes with a front bag, a rear bag, a 5� Center Section, a radio pocket, a pen pocket, and a double pocket.