This is the CamelBak "Marathoner Vest." It's a hydration vest for staying hydrated during sports like running and marathons. It's a product from a hydration product specialist manufacturer headquartered in California, USA. It has a hydration bag stored on the back, and you can hydrate through a tube. It features a lightweight, body-fitting design and was developed for runners (quoted). I purchased it but never used it, and it has been stored at home. I'm selling it to organize my belongings. It may be folded compactly for shipping. I appreciate your understanding. I will ship via either Yu-Pack or Rakuraku Mercari delivery service.