This is a new, unopened item. I am selling it because I haven't had the opportunity to use it. It's the perfect size for a 500ml plastic bottle. Made with the same Clarino material as school backpacks, the exterior is waterproof. The interior is nylon-lined. It attaches with sturdy hook-and-loop fasteners. It's durable enough for daily use. Material: Clarino Size: Approximately 9.0cm wide x 22.5cm high Retail Price: 3600 yen This is an optional multi-functional pocket from Ikeda-ya Randoseru, a cylindrical pocket that can be attached to the side belt of the school backpack. It's convenient for storing items like recorders or folding umbrellas, which can take up space in the backpack and make it difficult to fit other things.