Anti-theft device for large backpacks. It's a cage made of strong, twisted stainless steel wire. For packs around 55-100L. Uses a padlock for locking. I personally used it with a 60L pack. I bought it new and used it for about six months of overseas travel, so it shows some signs of use, but there are no noticeable stains or issues that would hinder its use. Please see the photos for other dimensions, etc. *It should have cost around 14,000 yen when new, so I'm selling it for about half price.