Workman's Vertical Formula Square Bag in black, exclusively available online and immediately sold out. It's said to be the strongest backpack. I bought it this year for my child's school commute, but it was unexpectedly too large, and I haven't used it even once. It's only been tried on. I've lost the tag. Currently, it's not available for purchase on the Workman online store, so I only have screenshots of the specifications. It has a steel frame inside, making it a very serious piece of equipment. For those who missed out on buying it, how about this opportunity? This bag cannot be crushed, so it will be shipped in a large box. Thank you.