This is the second of these bags that I've owned. They're 100% durable canvas and they've been great through most of high school and all of my undergrad. Like I said, though, this is my second. The reason is that, carrying heavy textbooks, the rectangular metal ring that holds the strap to the body of the bag tends to twist so it's vertical and over time (a year or two) it rubs away at your strap and makes it look all frayed. Though, by the time that happened, my first bag was so sun-bleached from my having carried it everywhere I went for 5 years, I didn't mind getting another. And I still use the first for day trips into the mountains sometimes. These are awesome bags, and in a few years when it's time to retire my second, I'm sure I'll be in the market for a third.