Our Messenger bag is 15"W x 11.5"H x 2.75" deep. Has an adjustable secure nylon strap. It comes with lots of pockets for packing smart phones, pens, etc.. The inside padded compartment holds up to a 15" laptop or notebook computer, power cord, mouse, and files. The outside is made from heavy water resistant 600D nylon. The interchangeable flap is made from a heavy weight canvas with a polyester front. The flap locks down with Velcro pads.