Past variations of those bags applied ripstop nylon. The current one uses a weighty-duty recycled polyester, which held up nicely during a six-7 days trip across Europe. It's very at ease. I'm shocked at how light it feels given its large size. I tested it through my daily office commute. https://yesbookmarks.com/story17499210/a-simple-key-for-bag-travel-backpack-unveiled