Full Grain Cowhide LeatherThe leather laptop backpack is crafted of 2mm thick crazy horse leather. Its surface has a retro rough look, quite durable and sturdy lasting for decades. The feature of this kind of leather is that it grows brighter and shiny with age amazingly. Update vesion has cancelled USB port and the bags are improved to be leather shoulder straps. Expandable Backpack You can expand the leather laptop bag wider up to 7cm. Roomy to store 15.6 inch laptop,A4 files, tablet, telephone, pens, cards, wallet, clothes. Size:7.5(L)x 4.7(W: before expasion) / 7.4( W: after expansion) x 16.5 (H); Weight:3.5lb, Shoulder Strap Length:67-98cm/26.3-38.6. Convertible to BriefcaseStructure: 1 front zipper pocket with 5 hang clasps, 1 pen slot, 4 card slots, 2 inner pouches; 1 main compartment with 1 padded sleeve for 15.6 laptop, 2 inner pouches, 1 inner zipper pocket; 1 side zipper pocket with elastic belt to hold water bottle