This is from the Uhaul website: "
U-Box storage and moving containers are made exclusively for U-Haul. Each U-Box container is made of premium, pest-resistant plywood, which provides your belongings with a stable and chemical free environment for storage and transit. This is especially important if you have wooden furniture. Our
U-Box containers breathe much better than steel containers reducing the chance for mold and mildew. Each container is also covered with a highly durable, weather-resistant cover when delivered. "
Glad it worked out well for you though. In the end that is all that matters. I was worried about trying to fit our king size mattress in one lol