The P.A.C.K. (Personal Army Combat Kit) Plus can fit 6 inches (152 mm) of foam. Its rugged, black Ballistic Nylon exterior protects a hard plastic interior built for strength and durability. Its design includes a zipper on the bottom to allow for attachment to the P.A.C.K. 1520 XL. Another zipper lines the top of the bag, which allows you to stack multiple P.A.C.K Plus bags together. You can also attach the P.A.C.K 216 or P.A.C.K 720 to the top of this bag. The P.A.C.K Plus was designed for airport travel and meets all FAA regulations for carry-on luggage.