Full Grain Calfskin LeatherThe mens leather convertible briefcase backpack fits 15.6 laptop (means diagonal length of a laptop). It is made of soft black calfskin leather, which belongs to full grain leather and is known as the top layer of natural leather. The pores of calfs' skin are small and fine. So the texture of calfskin leather is tight, soft, smooth, and also with great flexibility and durability. Expandable BackpackYou can expand the black leather laptop bag wider about extra 6.5cm/2.6". Roomy to store 15.6 inch laptop,A4 files, tablet, telephone, pens, cards, wallet, clothes. Size:11.4"(L)x3.35"(W: before expasion) / 5.9"( W: after expansion) x 16.5" -17.7"(H); Weight:1.43 kg/3.15 lb, Shoulder Strap Length:65-103cm/25.6"-40.6". Strap type: adjustable and hiddable into back zipper pocket.