That paper is called Indented Kraft paper. You can buy it by the roll online for cheap and cut it to fit your tubs and enclosures. It's super easy to work with. For extra messy snakes I just use a double layer. Just buy a roll at the cheapest place you can find it. It will last you a long time and pay for itself many times over. Just make sure you get a roll that is as wide as your widest enclosure. Or if you have 6'-8' enclosures you just overlap it.
http://www.stockboxes.net/store/kraf...per-rolls.html
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