This is a hydration pack from CamelBak. CamelBak is known as a specialized manufacturer of hydration products. A hydration pack is a water supply system built into a backpack, etc., allowing you to drink water directly from a tube. This product is widely used in outdoor activities such as hiking, cycling, and running. The capacity varies depending on the product, and the image shows "70 oz" (approximately 2.07 liters). (Quoted) I have not used this since I purchased it and have been storing it at home. I am selling it to organize my belongings. Although it is unused, the surface of the bag has become generally dull due to storage for several years. There are also some slight scratches on the plastic parts. I wiped it lightly with water before listing it, but please understand this and be aware of it. I plan to fold it compactly and ship it via Yu-Packet Post. Please understand that there may be changes to the shipping method.