This backpack from the KURO series uses reflective material on the triangular pieces, so when light hits it in the dark, the entire bag reflects light three-dimensionally. In bright light, the metallic texture becomes visible. It has a square, three-dimensional design. It's a convenient size that's not too big and can be used by both men and women. In addition to the exterior pocket, it has an interior zippered pocket that is convenient for storing valuables such as wallets and keys.