These are big Ziploc bags that are extra sturdy and have a carrying handle. There are two sizes: 2ft x 1.7ft for the XL size and 2ft x 2.7ft for the XXL. They only cost a few dollars.
There are probably a million uses for them. One great use we found is for our kids to bring bristol board projects to school. The bristol board is kept flat, clean and dry and is easy to carry. In the past we had to roll them up which resulted in them being curled instead of flat. Or placed in a green garbage bag to keep them dry which was awkward to carry and resulted in them being dog-eared and bent. The Big Bags would serve the same purpose for anyone who has to transport or store blueprints, prints, paintings, posters, etc.
— Doug Jones
* Expand as needed to fit where totes won’t go. Perfect for storing even your bulkiest items while helping to protect them from moisture, dust and pests. XXL holds the equivalent volume of a 75.7L tote.