13 shoulder drop 1.This backpack Made of High Quality PU Leather. 2.Inner Lining was Made by polyester. 3.The Interior Features: One Main Pocket, One Zipper Pocket and Two Small Opened Pockets. 4.Perfect for school, camping, hiking, travelling, sports, gym, and a holiday weekend bag. 5.Luminous effect: in the dark, or in the sun. Use light or cell phone flash to illuminate. The color of the bag will change into a magic color.